Not (necessarily) if you choose carefully.
My car - a 16 year old Golf estate - wouldn't have fetched more than £500 on
ebay for the last five years. During which time it's generally cost about £50 to get thru' its MOT (this year was zero, but that's unusual), plus the occasional few quid for bulbs and new tyres and the like (£36 a pop delivered, last time I got some).
Look for lowish mileage, some kind of service history, and a seller who doesn't strike you as an absolute rotter, and you could well get a perfectly reliable Jap/German car for that kind of money. Don't buy fancy, and don't buy French.
I say not necessarily, because you can follow all the above rules (and more) and still come a cropper - it's a risk you take at that price level. But £500 for a reliable runaround? Far from impossible.
Insurance will almost certainly be far & away your biggest cost for the first few years - there's not a lot you can do about that but suck it up & drive careful.