You have two options.

1: Wait until AFTER the ETH PoS merge. Wait until video card prices crash as miners go out of business then liquidate their rigs. Then buy cheap RTX 3060's for $200-250 each or RX 6800's for $300-400. With free power, you will probably make a 20%-50% per year return; then hopefully when the next GPU coin gold rush happens, you can make a 200-400% return in a year.

2: Buy video cards now and mine on them, hoping to sell them off right before the PoS merge. You're taking a risk with timing. However, PoS should take at least 6 months. Returns in today's market can be up to 300% at free power.