riding in some 30 quid duffs i bought in january, that i wear for all the scrubby jobs around the house, and then for riding there super comfy, really well mounlded to your feet Also got another pair of duffs(that i rode in once, but i didnt want to but they where still very nice for riding) in general you cant got wrong with going to your local freespirit/ckate shop, and seeing whats on offer, the chaeper the better, the'll just wear out.
Or a pair of plympsole based shoes (such as the dunlop shoes, converse etc) are ace for riding in, i wear them acosionally, really nice sole, fit well, and are very thin on the sides. and you dont look a full on gemp.
Cheers
Tom