I think average mileage is about 10k a year, so on a 1990 Golf, you're looking at about 200k, so 87k sounds really good, but sounds like it hasn't been looked after. As long as they've been looked after, they will live forever. Think the highest I've seen on a mk2 was 350k. As I'm sure you know, you'll tend to pay more for lower mileage, but prices tend to fluctuate so drastically. I paid £500 for my '91 8v with 187k on the clock, but now, I'd probably be paying upwards of £1000. All the best with the purchase