Situated in Digbeth, not too far away from the Custard Factory or the bullring is a big yellow shop called COW. Frequented by Birmingham's hipsters and anyone cool who is under the age of 25. COW imports it's clothes over from the USA and what may have seemed a bit naff over there is very cool over here. you'll find loads of shoes, accessories, and clothes from the 80's and 90's. My own favourite buys from Cow are my 80's Lou Reed T shirt with a rare picture of the man smiling on the front and ROCK N ROLL ANIMAL in big letters on the back. If you like strange oddities such as garish Hawaiian shirts or silk shirts then Cow's the place to go.If you want something a little bit less extravagant then they have loads of designer gear, racks of second hand but great condition Ralph Lauren and lacoste polo's. It's stocked up with all the best local free magazines and if you ask nicely you can get a reed bull. While an older couple once walked in an once remarked 'It's just an expensive charity shop' I maintain that compared with the prices most of the clothes there would cost new, pretty much everything there is a bargain. Cow also produce new clothes of very high quality.
Nearby in the Custard Factory things are not going as well, the loss of The Urban Village has been followed by Left For Dead, Provide, and Trunk Junkies. The only vintage shop left there now is Flamingo a little shop opposite Yumm, they have a spiral staircase and a nice retro feel throughout. It's mostly moddish, retro clothes. There's some nice stuff there.
If you don't mind hunting to find the best threads then Credit Crunchers is a good place to visit. not that far off from a charity shop. As they don't pick out the best stuff for you but because of that a lot of the clothes are amazingly cheap. I've not found much there worth getting, but I always keep looking.
Harper & Lewis seem to be everywhere at the moment. They've had pop up's all over Birmingham. But now seem to have settled on 2 stores. One being the store in the bullring, which has been a success since it opened. However your better going off the beaten track and going to the one in Oasis. It's the same clothes, and mostly cheaper. It's worth keeping an eye out for more pop up's. The last one where you could fill a bag for a £5 were full of bargains.
Oasis is also home to REVIVAL. While Oasis is full of great stalls Revival is the only other genuine vintage stall. Full of mod/skinhead/rocker fashions. With plenty of cool brands and unique finds.
I think that about covers it.