Get as much as you can afford. Itās all about cfm & recovery when running die grinders & other air hungry tools. But you already know this.
Even a budget friendly unit big enough will still be $800-1000. If youāre spending $500 already, throw a little more and just get a Horror Fright or something from Home Despot (Husky), it will be worth it for less frustration at lack of oomph!
Last January I was able to get a new Jenny 60 gallon, 14 cfm delivered air. USA made pump and tank, itās a beast.
Industrial strength but it cost $1500+tax and $300 shipping.