How to Structure an Offering that allows for buyback

How do you get investors to cap their upside? If you can, find investors who agree to that without asking for anything in return + have other capital sources that permit it (seems difficult). Or, more likely, you're going to have to give up somethings you'd want otherwise -- better pref terms like high coupon, guaranteed return, liquidation preference / security (again, impacts on SBA or available capital sources), put rights, special voting rights, etc. The more off-the-beaten path your structure looks, the smaller your pool of beaten-path investors with ordinary expectations will be interested. But there are lots of angels and alternative investors out there that are creative and ambitious; if you forego SBA funding, you might be able to carve up a unique capital structure.

If you concern is not so much about buying out investors as it as about getting additional upside to yourself, maybe explore incentive-based compensation for yourself -- bonuses and additional options that kick-in upon milestones for example.

This, in my view would be a big negative because of the upside cap. Additionally, this won't, to some make you look good in that some will view this as "gee, use my money, find unicorn, cut me out" type situation. Not a fund I'd consider.