Boardman - excellent hybrid and about 4 different models to choose from.
Just make sure that when buying through e-bay you dont get carried away and pay over the odds. Look for completed listings to gauge a reasonable max price. Look at their feedback, contact them beforehand and ask some questions, check how they will package it up (I made a massive error here some months back).
Gut feel tends to work. Alternatively try gumtree.co.uk Depending on where you are in the country you might get a good choice and can view before buying.