The AX never really had the cult following of the 205gti or the R5gtt etc, and its very hard to value such an old car.
With having such low mileage, it would be difficult to find another that is similar so it would only really be worth whatever someone would be willing to pay.
To be honest, it just seems that the owner is chancing someone wanting to relive their youth rather than the car appealing to a collector or the same 'retro' crowd that a mk1 Golf or 205 would.
If you want it then make an offer, but remember that the car shares the vast majority of its underpinnings and mechanicals with the non injection (very early) 106 XS. On that basis it doesnt appear to be so appealing, does it?