Nah Vean,
You are being steeped a bit there. Seen your thread on the classifieds....
To give a ballpark, I just sold a Spyder Electra with a Smart Parts aftermarket Barrel, Spare Barrel, Charger, Battery, Co2 bottle, and barrel condom for £90.
If you ask on the classified forums for a blowback recball marker, ask for the full set-up and set the maximum you're prepaded to spend. There's a lot of guys out there with blowback backup markers that they'll part with for a reasonable price....but bear in mind the price i've noted above...a revvi hopper should only add £20 to that if it comes with the set-up.
(Also make sure if you buy a blowback that you DEFINITELY only want to play recball...you could be better splashing the extra cash for something a little more tournament friendly, and you'll kick yourself if you buy a blowback now and end up with the depreciation when you want to sell it after only a month (Been there!)