Here is an easy and cheap way to roast your own coffee that produces pretty good results (with a little practice). I’ve been using this method for a few years now. Buying green coffee beans is cheap and if you store them in a cool dry place they’ll happily keep for a year or more.
I roast coffee in batches of around 250g. The beans are at the nicest to use about a week from the roast date after mellowing a bit, and are best used within one, possibly two weeks after that.
Using a store bought heat gun (with adjustable temp) and a stainless steel bowl, it will take around 15 minutes to roast a batch of coffee. Do it outside or you’ll be cleaning up chaff for days!