"No money" means no down payment and no mortgage, because you never take title. It doesn't mean no cash.
The out-of-pocket items on one deal are the earnest money deposit, which is the good-faith money you put up when the contract is signed and can be anywhere from $10 to $1,000 depending on the seller and local custom, your marketing to find the seller in the first place, and possibly a title search. If you're cold calling rather than mailing, a realistic first-deal budget is a couple of thousand dollars. If you're mailing, $2,000 buys you roughly 3,000 postcards and no guarantee of a contract. Marketing is the real cost, and it's the one people leave out of the "no money" claim.
On the funding side, transactional funding is short-term money, often for a single day, that lets a wholesaler close with the seller and then immediately resell to the end buyer instead of assigning the contract. Pricing is usually points on the purchase price or a flat fee, whichever is greater. Underwriting looks mostly at whether the end buyer's funds are already sitting in escrow rather than at the borrower's credit, because the lender's exit is that second closing happening within hours.
It's a real product and there are more than three providers, though it's a narrow niche and terms vary a lot. Get any lender's fee schedule and payoff conditions in writing before you commit either direction.
One thing to check early: not every title company or escrow agent will handle a back-to-back closing at all, and the practice differs by state. That single phone call decides whether the whole structure is available to you.