I have a 2001 leon 20vt sport (cupra), I bought new, that is just done 100k.
I have done the last 70,000 miles with a Jabbasport re-map to 220bhp and a Forge DV. I had the turbo changed (by Seat, £1400) at 80,000 miles and this made a huge difference, it really picks up well now.
The cam belt kit was changed at 35k when I had trouble with the pump, and i have just booked her in for 100k major service and another cam belt. All work always done at SEAT.
My leon has done over 50k of the 100k on the M5 so clutch, suspension etc all still ok. A 50k car, that been thrashed around town will probably been knackered after 6 years, so you really would be better off with one that has higher miles, loads of history and only a couple of owners.
I love my leon; its fast comfortable, reliable and can even do 40mpg if you are carefull!
I have been looking for a replacement lately, but cant find anything I like. The new Cupra is ok, but I really dont like the interior, looks a bit naff IMO. I have driven all the latest crop of hot hatches and the only one I liked was the Golf GTI! (how can it be £20k?) In all other instances, I was v happy to get back in my beloved Leon.
Hope this has helped
byeee