I would say £4.5-5k would still be a good purchase price, if thats the car your after?
Parkers
Guide prices
2.0 WRX STi 4d (03)
Original Price£25,995
Franchised Dealer £4,635
Independent Dealer £4,235
Private Good £3,985
Private Poor £3,285
Part Exchange £3,540
The prices above are based on:
A mileage of 90,000 (average for age)
A quick look around for same(ish) spec suggests £5k+ some even with more mileage asking for similar money! so selling above book price (as always)
Only query I would have would be the 5 previous owners!! current owner makes 6 and you then become 7th?? would be good to check length of ownership of last few keepers...alongside the history.
Looks good though and worth a visit with some cash in your pocket
Start face to face offer at £3.8k if bids have not raised on eBay, if its not accepted, bid the same price on ebay via your phone whilst there, to see if it goes past the reserve!! do this for every offer, should get it for his lowest price then
good luck with it, does look nice and decent bug sti's are a bit thin on the ground.