GPU programming is usually used to refer to CUDA and OpenCL etc. I don't think that is what you want, no?
As for shader programming (HLSL, GLSL, Spir-V etc.) those are pretty much available on all GPUs for x86 systems (Mobile / ARM is a different story) since many years, even Vulkan is supported on pretty much anything since 2013 or so.
If you want an older dedicated GPU still good for gaming then look for 960 and higher (maxwell) on the Nvidia side and 460 and higher (polaris) on the AMD side.