End-Investor profits

[Junior Salters]

Hey guys, I'm starting to get some leads and am about to visit properties. I have done some comps and am now trying to figure out the scaling for what my wholesale fee should be. I've talked to a few local investors and one guy looks for 15-20k profit on every flip he does. I heard other investors who like to make a % of the end sale such as 12-15. Is there any rule of thumb to make sure I get my end buyer a big enough profit, while also not cutting myself. I know they're taking the bulk of the risk so I definitely want them to succeed. Or basically is it a preference thing? Thoughts?