I think its worth selling mate - provided it's reset first.
If its less than 12 months old Superchips will reset for just the price of carriage (they charge £6 I think). If its more than 12 months old then the cost is over £300 inc vat from memory which then takes it mighty close to the £390 you can get them from JKM. Map has to have been taken off the old car for the free reset to apply also!
I bought mine off ebay recently from a decent seller - paid him £150 originally, as I thought the free reset would make it a bargain - turns out he hadn't removed it from the old car so Superchips wanted the full £300+. ebay seller refunded my money and said I could keep the handset!!
Superchips also agreed to a price of £238 + VAT as someone previously gave me incorrect info on the phone!
HTH (although I might have confused matters more!!
)