It's imperative that you have a clear understanding of the calculus from a revenue and expense perspective - you are after all, expecting to compensate your sales people on revenue (or margin).  Based on a cursory look at your website and a very crude understanding of your product offering i have a hunch that a direct sales model simply won't pencil out - happy to be proven wrong. I encourage startups to start with a direct sales model, even if a direct sales model won't pencil out or scale in the long run, simply because there's no substitute for the high touch that direct sales give you with prospects, customers and partners early on.  If your model needs to transition (or start) to a marketing only model that's fine, but everyone needs to go in with their eyes wide open - no sense trying to fool yourself or your early team.  Believe me, a sales person worth anywhere near their salt will pencil out the numbers before the first cup of coffee is gone - assuming you want people with some grey-matter between their ears.  

SaaS startups that lack sales expertise, but have a co-founder with extensive marketing experience can be successful going with only marketing (no offense to the marketing folks) right out of the gate, but it's not clear that you have this skill on your team either.  That's (marketing) a very different discussion than "how do i get and recruit commission only sales reps to sell my product...".   

So, since you asked, for rough calculations assume that compensation for a sales person (or team) will roughly mirror that of a software developer (or dev team) with perhaps a somewhat broader scale from low-end to high-end. Forget adjusting for a risk premium just yet.  So, for talking purposes only and allowing for the usual adjustments such as location, a green CS grad will likely command somewhat more than a sales person with equivalent education and experience - very roughly ($50k-$70k V $40-50k), exceptions certainly abound on both ends of the scale.  On the upper-end a software developer with a MSCS and 10+ years of experience will likely command a bit less than a sales person with a MS/MA and 10+ years of experience (very roughly $100k-$180k V $100k - $300k+), though for sales people much more dependent on industry and track record.  Again, very rough numbers, but you get the idea.  The scale continues for equivalent titles (manager, director, VP, CXO).  The BIG DIFFERENCE is that it is very rare for a software developer to agree to base their compensation solely on directly measurable performance - i.e. "pay me on revenue" or "pay me when the product launches" or "pay me when we have x,xxx customers".  For a SW dev the calculus is typically very low risk and thus there is typically no to low risk premium.  For a commission only sales person the risk is very high, especially for a startup, and thus the risk premium is commensurately high - very high.   Limited dev resources in a startup magnify the risk even more for the sales person.  Imagine you are a commission-only sales person and you 'make' a bunch of sales, but you don't get paid until customers pay and customers don't pay until they have a working product or a certain feature set and that product or feature set is dependent upon the performance of the dev team... who are not compensated on revenue... or performance.  In your case your risk premium is quite high.  According to your website you are generating gross (net really) revenue (roughly) of $240k over 6-7 years or about $35-$40k/yr.  Even at 100% commission that won't get you past a cup of coffee.  So given that you don't have extensive experience in sales or recruiting, vetting, hiring and managing sales (or marketing) people and designing sales comp plans i just don't see how you can make this pencil out - unless i'm missing something.   If you can find a way to make the numbers pencil out, you still need to plan to hire a somewhat rare bird. This person doesn't necessarily need to have all the above experience (recruiting, vetting, etc.), but it would be a big plus if they did, but they do need to have at least mid-level experience in sales in an applicable industry, they need to buy 100% into your vision and be passionate about what you are trying to achieve and you will need to show them a very clear path to a risk-appropriate compensation plan that gets them out of bed every morning ready to perform super human acts.  And they probably should have significant marketing experience and a marketing degree because i have a feeling that you will need to transition away from a sales mofel to a marketing model very soon.  Again, in very rough numbers, that's probably a very clear and realistic if not conservative path to $100k ARR (their gross comp) within 6 months.  To induce them to perform super-human sales acts that's probably more like $200k ARR (gross, to them) within 6-12 months with some equity too. Obviously the clearer the path and the higher the passion and compensation the lower the comp can be.  Remember, just like developers who have passion and do side, open source projects, sales people are also passionate about certain markets/causes, but they need to pay the bills too.  

If you stand even a snowballs chance is hell of recruiting a commission only sales team worth the effort you MUST be very clear on the numbers and the risk and you have to be willing to compensate them very well and you MUST be willing and able to step through the numbers with the potential new-hires in a clear and convincing manner.  That's likely a detailed revenue and expense model of months 1-12 plus quarterly of years 2-5.  This model needs to get very detailed and must withstand the sniff test that any decent sales person will give it.  If you were going to convince a SW developer to build your product for you and compensate them only on a % of revenue or net profit what details would you need to show this developer?  

Often times it's hard for technical folks to get their arms around the concept of sales 'hacks' making at or above what technical people make.  Give the reputation that many sales people perpetuate and sometimes deserve that's no wonder. I'm a recovering engineer, i get it. I used to manage engineering teams and sales teams - i get it.  I also have a lot of experience selling (SW and SaaS), recruiting, vetting and managing sales teams and designing compensation plans.  I was a VP of sales for, at the time, the worlds second largest software company - publicly traded on the NYSE (still is).  I can tell you that there was always at least 1 sales person on my teams who's W-2 exceeded that of the CEO and all of the CXOs in the company.   That's just the way it works in sales and that's what you want - ethical sales people who will move heaven and earth to help you achieve your targets.