Wholesaling is often held out as a "quick and easy" way to generate cash. Often by gurus who's only real goal is to sell you on classes. That is, to separate you from that $20K. They're selling a "get rich quick" scheme.
I suspect its neither quick nor easy. For all intents and purposes, "wholesaling" is "real estate brokering". You're putting sellers and buyers together and collecting a fee. Yes, there are all sorts of techniques to avoid it becoming unlicensed brokering, but the fundamentals of the job are the same. You have to chase down deals. You have to chase down buyers (because you lack the huge aggregating advantage of the MLS.) I would focus on doing both.
I don't think REOs are a good source of deals.
1) They're already on the MLS and readily available to anyone who wants to buy one.
2) You're not going to get a radically discounted deal vs. what they're listed for on the MLS. Banks may come down a little, but you're not going to have much success offing $50K for properties that are listed for $100K
3) The selling bank is going to do everything in its power to make your deal fail. They're taking a loss, and they just don't want a wholesaler to take a 5% cut out of the deal. You'll end up doing transactional funding or some such to deal with their restrictions.
Start with marketing directly to various lists. Landlords who have recently appeared in eviction court, code violations, fires, probate, out of state owners, properties with back taxes, properties that look abandoned. Basically, people who may want to sell, but just haven't taken the action to get the property cleaned up and listed. Find buyers who are willing to put some work into the property and are able to buy multiple deals and pay cash or have flexible lenders. Move-in ready pretty houses are sold to retail buyers (people who are buying with conventional loans) through the traditional MLS/agent system. REOs are also sold through the MLS. If you're going to deal with these, you have to figure out how to add value. If that $209K house is really a source of $150K in profit, some investor would have already bought it. As a wholesaler, you're dealing junkier properties and investors. Find deals, find investors, put in a LOT of work and you might make some money.