over 3k easily - its the right colour, right spec, right mileage and FSH.
A 96P mystic blue with 95k in good order sold on ebay this week for 2400 (not much mention of history)
For info, i was at a car auction a few weeks back and a blue met 98 R reg (not a nice blue met) sold for ?2100. However, it was a mess, dents down one side (proper dents) and serious rust on the other front wing (it was holed it was that bad) and 125 k on the clock. It ran OK - but yours should easily be worth 2800 at auction - so 3-3250 private is realistic.
I know all this as I'm about to flog my mint low mile Mystic blue thats a bit older than yours. The problem I find is that there are many 'ropey' GTis around and a surprising amount with major body corrosion / repaired damage / no SH / tatty / badly modded etc. The buying public see the low prices of these and expect to get my mint car with full history, completely original docs etc for the same price?

I'd keep it once the Boxster arrives, but its a real hassle insuring 2 cars