Yep, I've seen them in Tesco the last few times I've been in. £70 I think.
In regards to your present equipment, I don't know. It depends on how you've got it all connected at present, and what connections your TV has. I can't look round the back to check (as I'm at work), but I think there's two scart outs on the back of the Top Up TV box - one designed to go to TV, and one for VCR/DVD. I'm pretty sure it comes with a few other types of leads too though. Well worth the price, IMO.