We own one. We bought my girlfriend a 2001 TDI Beetle last October for $5500 with 120k on it. She loves it. She gets 45mpg on an average tank, 50 if we use it on an all-highway road trip. The interior is a tad rough because VW used some pretty soft coatings on the various interior panels that end up showing scratches very easily. The check engine light was on when we bought it because it needed new glow plugs, which were very easy to replace. The car feels very solid. I love the brakes. The clutch has good take-up and feel. Steering is very tight. Could use new struts though. Cargo capacity is really nice, especially with the rear seat folded down. Nits: I don't like the controls for the cruise control, and there's no 'you left your headlights on, dummy' buzzer. Oh, and the three 12v sockets in the car are constantly live. Between this and the lack of a 'lights on' buzzer we've inadvertently run the battery down overnight twice.
BTW, KBB says a TDI Beetle in my area in good condition with 41k miles is worth $6290, so unless something big is wrong with the car I'd say $5800 is a good deal.
EDIT: Sorry, I misread and thought you were looking at a TDI yourself. KBB says that car in my area would be $4080, so yeah, $5800 is high.