For £25 you'll probaly only be looking at an Egg2, I've one that I'll do for £25 plus paypal and postage if you're interested.
Has the z-board fitted which gives a few extra BPS over stock and has the battery mod done so there is little or no pressure on the door. Shells are dyed blue, not a great job but were like this when I bought it, looks a little shabby but works fine, was my spare before I bought another halo.