The real cost is your time. Projects always take longer than you expect, especially if you haven’t done it before (the business part). Product is the easiest and has limited risks if you have decent dev skills.
Enterprise is also one of the hardest markets, not only technically, but also getting clients (3-12 months from first contact to money in the bank is normal). Enterprise is also a game where they don’t buy the best software, a lot of factors play a role in getting enterprise clients. It’s doable but definitely playing a new game on hard/insane level.
Focus on the problem that you solve for the business, without a very strong case for that and be able to gain a champion within the company you are selling to, it’s near impossible. As you can see its more about sales, and connections, and less about product.
I’ve been in your situation before serving enterprise SaaS as a two-person company for 5 years. It was very hard and I would not do it again. Then again, once we got clients they were easily paying $30k/yr with long term contracts in place. High risk, high reward.
If you are starting out you have different levels of risk you can take. Since your real prime-time years are at stake, are you going to play this game on hard right at the beginning? I’d suggest to start on easy, get more experience, and as you grow, level up. Once you have a couple $$$ in the bank, do bigger projects with higher risk/higher reward ratio.
That’s what I wished someone told me 10 years ago.
If I were you in this situation now, I’d first warm up those connections, as they will play a crucial role in your company. Is it something they want or need? Is the pain they are experiencing so hard they are willing to prefund the project? If you think so, try convincing them to get either dev money beforehand (hard) or have them sign a binding (hard) or non-binding (doable) agreement to pay xx amount when the software is ready. Include what features/problems you will solve in the agreement.
Your ideas about profit sharing are too complicated in my opinion.
If you are not able to convince them to prefund or either sign an agreement, for me personally this would be already too high risk. Unless those connections are decision makers and you play golf every month with them ;)
That’s what I would do in your situation and my 2 cents.
Wish you all the best of luck, not want to discourage you, but sharing my own experiences in a somewhat similar situation. If you need advice, help, or just wanna bounce some ideas, always willing to help out fellow entrepreneurs.