Consumer CPUs don't have enough PCIE lanes to do that. Even if they had physical x16 slots, at most two of them would be x16.

What's cheap to you? You can find Epyc 7002/7003 boards on ebay in the $400 range and those will do it. That's probably the best deal for 4x PCIE 4.0 x16 and DDR4. Probably $500 range with a CPU. That's in the ballpark of a mid to high end consumer setup these days.

If your actual gripe is risers, sounds like a "you" problem, not a technical problem.