Having been a patent examiner and a patent prosecutor before started practicing exclusively as a litigator for the past decade, I offer you the following advice:
(1) Never hire a cheap patent agent/attorney. Treat it like you are looking for a co-founder. Creativity, not regurgitation, is what you should pursue in patent drafting. Any qualified patent attorneys can regurgitate what you have invented or written in your white papers. The challenge lies in the attorney's keen ability to envision nuances in your space and provide enough written support and disclosures to cover them. This skillset is even more critical if the relevant space is over-crowded with competing inventions and obvious variations. A well-written patent, therefore, is one that could carry you through the next 20 years of technological advances; one that doesn't become obsolete before you pay your first maintenance fee. There's little incentive to pursue a short-stint or "stale" patent; the cost-benefit analysis simply doesn't add up. What most applicants desire is a patent that would still be relevant in that space now and decades beyond. With a low budget, a patent attorney has little incentive to help you conceive all of such nuances. Most patent attorneys work under the billable hour structure. The proverbial best-bang-for-the-buck model does not work in the patent space.
(2) Never draft the patent application yourself.76% of the pro-se applications become abandoned before issuance (compared to 35% of "represented" applications). This invalidation rate is even higher, actually much higher, for patents written by non-patent lawyers. I could not recall a patent written by a pro-se applicant who has successfully survived patent litigation. A poorly drafted application might put a dent on your bank account in the short term, but a poorly drafted patent could cause collateral damage to even a well-run business for years to come.
3) Provisional application is strategically useful and commercially advantageous if and only if it offers complete and unequivocal written support for the subsequent utility application. Otherwise, the provisional application is effectively meaningless (as it provides no legal recourse for you should the priority date be challenged). Most well-executed companies and businesses generally approach the provisional application in the same way as a utility application (i.e., draft it with a full-blown spec, figures, and a set of claims). This particular approach ensures that there's little to no dispute in litigation as to the written support for the patent disclosures. If your intent is to file a provisional application with some kind of hand-sketched, chicken scratch diagrams or description, please let me counsel you against doing so. Patent examiners are highly trained on spotting priority issues. Knocking your priority down gives them a bigger universe of prior art. A poorly drafted provisional gives you no leverage during prosecution. In that case, you should consider filing a utility right off the bat.