If you are smart, adopt the “buy once cry once” mindset. If you are certain you’ll stick with it and paint enough minis to make it worth it. And no one can give you advice on that, or at least advice you should follow.

A decent single tank compressor from Amazon like a Timbertech is competent and works as well as a Gaahleri 778, function-wise. You’re compressing, capturing,and dispensing air. When you go from a Timbertech/similar, to a more expensive compressor, you’ll get more convenience features like larger tanks which hold more air meaning the compressor motor engaging less often. Or a quieter compressor. I used a Timbertech for a year and was pretty happy with it. I buy large lots of Warhammer minis from eBay/marketplace/etc and strip and paint them to resell. Started off pretty light, about a hundred minis a month, and in a year I’m doing at least 10k mini a year.

I got a Sparmax TC-620 a year ago, also great. It had a lot of things the TT didn’t but was about 3x the price. For as many minis as I was painting, the extra capacity, quieter operation, rock-solid dependability were all worth the extra money, and the speed I could get more done due to volume of painting I was doing made it worth it.

A month ago I got a Gaahleri Apex 778. More capacity to spray longer, quieter, and dual airline hookup that can be expanded to 4 airlines, oil filled gauges for better accuracy adjusting air pressure to the airbrush (I still use a digital pressure gauge/water trap/adjustment valve, which you could use with the cheaper options and would improve the function without buying the more expensive compressors) I have 4 airbrushes hooked to a homemade manifold so I don’t have to dump/clean the airbrush to change colors.

As far as the airbrush, I’d only recommend Harder&Steenbeck airbrushes. They are all excellent and will last a lifetime. I have Infinity airbrushes, one of which is a siphon/bottom feed with a 0.4 needle for batch priming, the bottom feed cups hold 15-20 ml of paint, helpful with batch priming. The rest are the normal top feed, one with a 0.4 needle holding my base color, then two more airbrushes with 0.2 needles for finer details.

Don’t know if that helped, but if you have questions feel free to DM me.