The problem lies with the cost for parts factor.
If I go and build a car from spare parts from the wreckers, it would cost me more than a complete working one.
Because ive built this car with spare parts does the money spent equate to a market value? The answer is no.
Its entirely up to you whether you buy or not.. it is a desirable title but the fact its still for sale tells the story regarding price.
If you can snag it at $2500 and are willing to do the cabinet yourself then I guess you haven't overspent too much... I have stencils for FP at $150 + postage. Paint will cost $100 and your labour is free. That gives you a very nice machine for under $3K.
The proof of the pudding is in the eating and a willingness to use decals instead of a repaint tells me the seller likes a short cut.. chances are that this approach will be evident throughout the machine so id be going through it with a fine tooth comb before any offer is made.
Bear in mind that I bought a fully working CENTAUR with 10/10 backglass, extremely tidy cabinet and minimal wear on the PF for $2200 on Ebay... if you go to another forum ( who control pinball pricing in Australia) then they will tell you its worth over $4K and yet I know of another 5 or so centaurs that sold around the $2K mark, many of which came from Ebay.
If you are sure your heart is not ruling your head then do what you think is best... but the shine will come off your purchase shortly after the thrill of the chase ( as it always does) and IF you come to move it on, will you recoup your outlay?