What Type of EC2 Instance Should I Use?

Currently I am on the free plan. I am running a python web scraping on a windows script that could be refreshing potentially every minute for tracking several different (20-50 instance requests at a time. Hopefully expanding to more. What infrastructure should I be using, looking for cheapest possible option. Also the web scraping instances are tracking elements on a site that could potentially ban or timeout requests. My python script is connected to a proxies.txt, I am wondering what the best proxies or way to generate proxies is?