This whole idea of "fairness" with pricing your wholesale deals strikes me as silly. This is a free market economy, and its not about fairness. It is about supply and demand and the price you "should" sell your deals for is determined by the market.
An experienced investor will most likely have a definite price that they will pay up to for a particular house. Let's say its a $100,000 house and the house needs $15,000 in work. Let's say the investor works off of the 70% of ARV Minus Repairs model that is commonly discussed on this forum (though most rehabbers I know do not use this model). That means that the investor will pay $55,000 for the house (100,000*.70 - 15,000).
Now this is what I know. Whether I bought that house for $52,000 or $42,000 or even $22,000, I could probably sell it in a day for $55,000. And I absolutely feel NO need, desire, or pity to sell it for less than $55,000, no matter what I bought it for.
The whole idea of basing your sales price on your purchase price is flawed. Actually that very mentality is what leads to newbie wholesalers trying to sell lemons as "smoking" deals.
Your sales price should NEVER be based on what you bought the house for. Your sales price, as a wholesaler, should be based on what an experienced cash investor WILL PAY for the property. Figure that number out and work back from there. Whether you make $2,000 or $20,000 or 5% or 50% of that number, who cares?
When you can accurately figure out what you can wholesale a house for, then whatever you can get the seller down to below that number will determine your paycheck. The SALES price does NOT change, only your BUY price.
In my example, if you get the seller down to $52,000 then you made $3,000. If you get the seller down to $40,000, then you just made $15,000.
But to say NEVER make more than $___ on a certain deal, smells downright communist to me. Limiting your profit margins based on "fairness" to another investor who is going to make a great payday on the deal anyway seems ridiculous to me. If you hustle and find a seller that is willing to sell that house for $35,000, you just EARNED a $20,000 payday, and there is absolutely no reason you need, should, or have to pass a larger share of the profit onto your buyers. There is nothing immoral about not sharing more of your profit when you are selling a great deal to someone.
That's what a free market economy is all about, and I for one am okay with making as much profit as the market will bear.
On the reverse side, I've never once had an investor tell me, "Hey I know you paid too much for this property but I'll buy it from you anyway to help you out." With this whole sharing mentality, why is it that a wholesaler should share the profit on one side but not share the loss on the other? That whole mentality favors the buyer disproportionately.
My vote is to let the market determine your sell price, no matter what you bought the house for. Most of the time with my wholesale deals I get base hits ($3,000-$5,000), but every once in awhile I put one right over the fence ($15,000+) and that's just fine with me. :D