I’m going to spend a bit more time at my parents over the next few months (at least a week here and there it seems) so I was thinking of setting up a small budget studio in a room at their house for songwriting and music production. .

I thought I’d be asking here what a good list of items would be for this?
I’ll bring my computer snd try to keep things as software as I feel comfortable work but might buy or bring one of my synthesizers but other than that I’m hoping to record guitar through an amp sim or similar, and I’m also going to record some vocals but as room will be untreated I’m not sure how I’ll go in to get the best results or if I should just settle with recording demo vocals.

Trying to keep budget under 500 $/€ and this amount will exclude the instruments being recorded so it’s mainly a stable and good audio interface for Mac.
It might also a microphone for vocals and smaller monitors and even a good solution for recording DI-guitar.
I’m not really sure about amount of inputs (and preamps) I need but I guess at least two but do like the possibility to expand later on if I want to.

Thing is I do have an extra pair of monitors (or good and comfortable headphones) and microphones but if budget allows for something better and more suitable I’m not against including it and even stretching the budget a little bit.

This is only for hobby purposes, but everyone I travel away from home I miss my studio and the ability to sit down and work on ideas that hits me.

I guess what I’m basically are asking is what audio interface and monitors would be a good purchase for my situation? If budget is under €500/$500?

And if I can afford a microphone as well what should I get? I already have two SM58 and could bring one of them but if I would/should get a condenser microphone (or maybe a better dynamic microphone) instead which should I look at?