I'm assuming you have an i5 and 8gb system ram, and are looking for a vidcard under $150. If you must buy now, if waiting is not an option, then a 2gb AMD RX 460 or 2gb Nvidia GTX 950 which ever one is less expensive is my suggestion. I don't think a 4gb card in that range is worth the extra money, if you are going to be gaming at resolutions/settings that require 4gb then you are likely going to need a more powerful card as well.
In the next month Nvidia is supposedly going to release a 1050 and that might be around $150 but then again it might not happen.