CS.Trade
Buy with real cash, or trade in for a 50% bonus - either way, there's no way to cash back out.
cs.trade is a real cash shop, not a swap-only trading bot - you can buy skins here with real money like any other instant-buy site.
The other path: deposit your own items instead of cash for a 50% bonus toward your next purchase. We track cs.trade as one combined price - whichever of the two (cash, or trade-credit-with-bonus) comes out cheaper for that item.
There's no way to withdraw anything to cash. Money and trade-ins go in, skins come out - one direction only. It's also the same cs.trade behind this project's Trade-Up Flips tool (the 5% cut there is our own estimate, not an official figure).
Live, computed fresh from our own database - see the full comparison for how every source is measured.