this might sound daft but have a look down to a sportsworld shop if you have one near you, i got some no fear shoes that are a lot like dc and the like and are quite grippy on flats for under 20 quid.

I have a pair of old Vans that I use (Bucky Lasek signatures - they were nice shoes until they got sprayed in mud accidentally and it wouldn't clean off). Try the sale sections of surf wear sites like extremepie - depends on your size but there are bargains to be had. The only down side of skate shoes is their total lack of grip in mud when you put your foot on the floor but those waffle soles grips flat pedals pretty well if you have pegs of serrated edges.

And come to that, some time ago I got a pair of Airwalks for 20 quid in a World of Footblall type cheapo mega size football shirt emporium. It was full of pikey scum but for 20 sheets they were damn fine trainers that would be good for flats.

I got some Lonsdale trainers for £18 in Sports soccer in Hull. They feel stiff like my spd's but really grippy too. Much better than the Nike trainers that I was wearing before!

I managed to find some size 13 Vans in halfords for £18.50.

size 13`s!! for £18.50.....to (almost) quote dan: /  theyre a flipper bargain

and the biggest joke is I'm only 5 foot 7 inches tall. I figured they couldn't shift them as your average bike bloke has smaller feet and does not weigh 15 stone like me. finding spd shoes is almost impossible. if they have the right size than they will be to narrow. My feet are six inches wide.