My cofounder and I have scraped together our own funds and don’t want to miss the boat on our product. We also don’t have a lot of time to waste before our small funding disappears. We know we could start prototyping tomorrow and put something together in the next 90 days, but it may not be great given our current financial resources. We read a lot about iterating MVPs, so is this way to go? Just let it fly? Or should we take more time with this and spend more money (money that is in really short supply) to release a better prototype? What are your experiences with prototypes?
Assuming that you want to get a prototype to:
1] prove out your idea with customers,
2] prove that they want it and are willing to pay for it
3] and in the end, in order to get more funding...
Then the "lean startup" protocol is to the LEAST possible to prove your hypothesis that your potential "customer wants your product"
-- this is the minimum effort is needed, no more no less...
To use your words -- "there is no better prototype" to prove this, just the prototype that does prove this out.... Your iteration is to reach that critical mass of customer feedback -- "I am willing to pay $X for your product."
That is what you must design and test
-- and with positive results and ample market potential you should find investment to scale your idea into the market. ..
I'm unimpressed when I read questions like this.
firstly, put a survey together and get to market to actually validate the idea before making yourself bankrupt to bootstrap the product! its a famous trap people get screwed by, its called falling involve with an idea.
secondly, 90 days are you serious? with that timeframe get the hell on www.udemy.com , 1 of you learn to code and the other one learn UX/UI , and then just build it yourselves!
(its unlikely your will ever get an investor at a later stage if you don't have a technical co-founder)
This is from experience, trust me, learn to code and build it yourself!
The short answer is that a prototype should be disposable and built purely for the purpose of learning and gaining insights. It is ok to pivot and refine, as long as they are incremental improvements within the same scope of the issue you're challenging (as appose to random takes on an issue) and are guided by the evidence your've generated through testing.
I hope you aren't both starting with prototyping. Luck and timing aside, startups tend to fail not because they have failed to build what they've envisioned but because they've built the wrong thing and/or have assembled the wrong team. Fall in love with your cause but never with your first idea, it's wrong 100% of the time. So before prototyping or spending a dime for that matter, do the initial learning steps that don't cost much now and will save you money down the road. I would recommend Asha Maurya's "Running Lean" book, it's a short read and very practical. 90 days is plenty time to apply it and get to a fundable stage, even if seed funding.
Best of luck.