Tips for buying my first camper

Hello forum people, hope that you can also give me some useful tips and answers. 🙂 I want to buy a camping bus or a camper. Because my budget is rather low (500€+) I think that a larger model like an alcove is rather not in my price range. Nevertheless, I do not just want a larger car with lying area, but at best a car, in which I can at least stand upright. Think perhaps of a box van like an older Mercedes or a Ford Nugget. Due to my budget it can of course not be the latest model, but I would not wish to have to shower immediately to the mechanic in the first year. In addition, the consumption should also be to a more bearable extent; would have been before driving longer distances with it. Stand heating would be optimal and uphill it should not remain. Inside it does not have to be top equipped; for example, no wet cell (WC and Co.) or sitting area. Otherwise, I would have to work a bit with it on the inside. Thus, I ask you if you can not give me the answers to the models?