Hey Currency,
I think that's the best way forward - don't buy anything until you are sure of the value and don't get involved in the bidding war game.
I think someone I was competing with in this case was truly trying to play the system as I studied the bidding history. Seems his cunning plan was to enter a bid of £1000 to outbid me and get an idea of my maximum bid and then, once he established that, withdrew the bid (eBay gives you one chance to do this) and in the final few seconds tried to some method to 'snipe' a winning bid at a slightly more realistic amount.
I looked at his bidding history and this character had been doing this for a while - he had 161 withdrawn bids in the last 3 months! Turns out I won by 50 pence though.
I intend to turn the PC into a project and upgrade various components in due course (I won't be using eBay and buying them used). Turning out an expensive project though!