I purchased a box of 5 40mm fans off of Amazon. They don't have the same connector so I just swapped the connectors. This will also give me the ability to use one of the 40mm fans for the hot end when I replace the cooling fan. Octoprint is amazing. I will never go back to swapping out SD cards after using Octoprint. Really, you can do both. Just order a raspberry pi and some fans from Amazon. I think I only paid like $9 for 5 fans. https://www.amazon.com/gp/product/B0757LXKST/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

My case fan was making noise as well.

Have you ever used a raspberry pi? If not, just make sure you get a really good power supply. Also, you will probably want one of the newer ones that have built in WiFi.