If only old bikes appreciated in value like classic cars. ....
My 96 proflex set me back at least 1400 and it eas reduced, going by the sold prices on ebay id be lucky to see 300, maybe 400.
Basically it is worth what someone will pay so be prepared to be disappointed.
The razorback was one of thr last proflex/k2 bikes before the company pulled out of uk market so not many here. The rear shock is rather unique so is hard to find replavement chrapky.
My estimate would be 200 to 500, probably towatds the top.