With €500 to spend, finding a bitcoin miner that really pays off is tricky. I'd look at something like Avalon A1346 with 107 th/s which sound pretty solid. it was released since 2022 and it is still profitable until today. But here's the thing, your electric bill can totally mess with how much you actually make so keep an eye on that. You could also peek at some platforms that make mining easier and promise steady cash, might save you some headaches. Oh and I'd definitely play around with those online mining calculators like the asic profit ones to get a rough idea of what you'd earn. Just make sure to dig into it all before you drop any money on gear or services, don't rush in blind!