T1 pricing is still pretty unchartered due to the fact that not many come up for sale. Most of them (particularly early models) were ridden to death. It depends how early you want to go as well. Ive never seen a NOS V1 barcode come up for sale (1st or 2nd production runs). Ive actually only ever seen 2 NOS V1 Bardcodes in all my time collecting. 1 was on BMX museum and the other one is mine pictured below. So working out pricing is pretty hard...
Saying that if you just want a "survivor" I would guess one of the later models 2nd hand would be about £100 for a frame, or about £200-£300 for a complete.