Thanks guys. I don't think you'd get a Nagra IV-S for £500 now. They've shot up in value too. I haven't seen a serviced IV-S go for less that about £1200 recently. I did toy with the idea of getting a Nagra, but to be honest I just don't use them, so there's no point really. But I'm not going to let it go for peanuts, as I don't need to sell it.
Best wishes,
Charlie