Please, recommend a graphic card for CUDA running on GPU (currently, NVIDIA GeForce 820M)

I struggle to deal with CUDA for video processing in OpenCV, Tensorflow. The problem seems to be in the hardware I have as it is far from advanced. For example, my graphic card is GeForce 820M which probably too old and incapable for running CUDA on GPU according to information on the forums. Since CUDA on GPU provides boosted compiling, I decided to replace the graphic card for a better one. Therefore, I would like to ask your recommendations which graphic card is good enough to run CUDA on GPU with sufficient computation capability and a fair price for students. I would highly appreciate any advice.

Thank you in advance!