There are a ton of choices in the affordable studio mic world. Most are OK, some are really good. I've been using an Oktava Mk-319 as my large diaphragm mic for the last, jeez, 20 years maybe? Quite a good mic, in my opinion. They're a little harder to find these days, at least here in the US. Rode makes some very good budget mics as well.

The Sennheiser e609 is my favorite guitar amp mic. You can probably find a gently used one for well under $100.

I've been using the Behringer UMC404HD interface for a little while now, and it works great. For the price, it's hard to beat.