I think that people selling at that price are very hopeful. Phone only just released, and currently only available from Vodafone as an upgrade. Spoke to Samsung and they suggested Carphone Warehouse in about 2 weeks time for SIM Free and unlocked, which ties in to page on Expansys, who are always over priced and are estimating selling at £310 - and estimating 14th December. See
http://www.expansys.com/p.aspx?i=159676
If it is locked to Vodafone you should expect less than SIM free in my opinion.
Sorry, but hope that helps... If you tell me what you want for it in a PM - I may be interested, but would need to then get it unlocked myself.
Thanks & regards,
NickW