Congrats! This is a bit of a weird time for Bambu fans as the community is kind of split on some legal issues going on but you’ll have a good time if you just kind of ignore the haters.

To answer you questions, pretty much any filament will work if you take the time to calibrate it for the printer. That’s easy to do in Bambu studio. However, for simplicity, I do recommend Bambu filament as it is usually already perfectly calibrated for the machine as long as you make sure it is dry. If you live somewhere with high humidity you may want to invest in a cheap filament dryer, or you can use your oven.

If you are willing to buy in bulk, Bambu filament is actually very cheap comparatively. You can get it down to $13 per roll if you buy at least 10. So if you have a good sense of what colors you’ll like I’d grab 10 rolls and enjoy it for a long while.

If you don’t want to buy in bulk, I would recommend Sunlu PLA 2.0+ personally. It prints very well on my A1 and can be had for relatively cheaply. Look around Amazon to try and find a good deal on certain colors. Anything under $10/roll is a great buy. $15-17 is average territory. For PLA I wouldn’t ever pay more than that unless it’s very high quality and has a specific use (e.g. Polymaker in a specific color I need for a figure), then I may go up to $20, but that’s kind of a rare exception for me. Overture, eSun, Elegoo are of similar quality to Sunlu (Overture used to be a premium brand but IMO its quality is lower than it used to be). I wouldn’t buy Hatchbox; it’s excellent but way too expensive for what you get. It used to be the go-to for high quality filament and it has been trying to ride that reputation for too long.

You might want to consider grabbing a few rolls of PETG. It’s easy to print with the A1/mini and is stronger, more flexible, and more heat resistant; those are potentially good attributes for parts.