Are there any? I saw a couple of OCZ ones for around £110 but I don't know if they're any good. I gather the performance jump between different SSD's isn't that significant, but the jump from a HDD to SDD it galactic, but is there anything to watch out for on budget-ish SSD's?
The performnce jump between SSDs can actually be very significant, but yes, it's generally much smaller than that between the average consumer hard drives and the cheaper SSDs.
The only SSDs of such capacity that I can think of at those prices are mostly either older models or OCZ's Agility models. The Agility 3 is best avoided due to reliability issues, but Agility 4 is better there and isn't a bad buy.