You’re right, 1:1 trading is basically extinct. The most efficient way now is definitely "liquidate and buy." I did the math recently and ended up using https://avan.market/market/dota2 for the "buy" part of the equation. Their market prices are consistently lower than most of the big-name competitors. What’s cool is that you can often find items that are already "clean" (no weird gems or sockets) or even pre-gemmed for a bargain. Instead of losing 15% to Steam and then another chunk on a bad trade, you can just find the exact item you want on their market and pay the real price. I managed to consolidate a bunch of random trash into a very clean Dragonclaw Hook this way. It saves so much time and nerves.