Hi Orlando,
We avoid all this by purchasing the property with another wholesaler. Teaming up with someone who has the cash to close has been huge for us. We don't have to assign any of our contracts so the seller never knows the profit we make when we do the final sale. The arrangement we have is this: we find the deal, he makes the purchase, both parties look for an end buyer, and both parties split the profit 50/50.
If you don't know a good wholesaler with cash in your area that is willing to work out a deal like we use, then just do a double close if the profit will be over 5k (or come up with what your threshold for a double close will be). For the smaller profits, just be upfront and honest with the seller. We typically explain that we may not purchase the property ourselves and to help mitigate our own costs/risks, we might make a few thousand to get the deal to the closing table. If they get all up in arms with that over a few thousand, then it's not worth the headache. If you think the deal is good enough to get 5k+, then just do a double close.