Yeah, that's a tough one. Digital i guess? Analog ones go for really cheap (under €50) with nice lenses already attached to them, but i wouldn't wanna live without live-view anymore. Waiting to find out if your pic is actually good isn't something i really miss 
The Sony alpha 5000/6000 (mirrorless) are supposed to be great for adapting old lenses, but for starters pretty much all entry level DSLR's are really good these days. Sony alpha 58 (around €250 used), Nikon 3200 (about €250 used)/3300/3400, Canon eos 1300d (under €300 used) are all good to get started and will get you great pictures if you know what you are doing.
However, I wouldn't call any of those cheap though, but you have to keep in mind you can get years, or a decade, out of them if you treat them right. I still own a Sony alpha 100 (over 10 years old i think) and it works just fine.
Don't go for compact cameras or ones with fixed lenses. Not worth the money and a dying breed imo, you can juse your smartphone camera instead and it'll do fine most of the time.
Edit: I didn't double check the prices, but they should be about accurate.
The Sony alpha 5000/6000 (mirrorless) are supposed to be great for adapting old lenses, but for starters pretty much all entry level DSLR's are really good these days. Sony alpha 58 (around €250 used), Nikon 3200 (about €250 used)/3300/3400, Canon eos 1300d (under €300 used) are all good to get started and will get you great pictures if you know what you are doing.
However, I wouldn't call any of those cheap though, but you have to keep in mind you can get years, or a decade, out of them if you treat them right. I still own a Sony alpha 100 (over 10 years old i think) and it works just fine.
Don't go for compact cameras or ones with fixed lenses. Not worth the money and a dying breed imo, you can juse your smartphone camera instead and it'll do fine most of the time.
Edit: I didn't double check the prices, but they should be about accurate.
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Pentacon 135 2.8 being next on my list.
