It really depends on the spread if I use assignment or flip/resale the deal. If your margin is really low, you might want to assign it and most of the buyers for this scenario would be wholesalers, who know how the business work. You basically should have a buyer's list of wholesalers that you contact when you want to assign the contract.
I usually charge anywhere from $1,000 to $5,000 for an assignment. Again, I use assignments only if there is little spread. I have a contract that i use for Assignments, so it helps to avoid wholesalers going "around your back." Just contact wholesalers that advertise on Craigslist or other media. Go to local real estate investors meetings. Building a ready and able buyers' list is crucial for assignments or flips.
If you have a larger spread, sell the property as you would sell any deal. I would still price it well below market, to get it moving, but you can advertise on Craigslist or your list of investors buyers (who are not wholesalers). You don't have to disclose your purchase price.