Best low cost or old GPU to play

I don't know what's that, what CPU?
Either way, the bottleneck is the CPU, what you want is a GPU that is decent enough to support Vulkan with active drivers not bottleneck the CPU, if you want high performance in PS3 games you'll need a CPU upgrade.

For GPU, find anything that falls under the recommended requirements, I would say at least around GTX 1060 / RX 480 performance.