Try gumtree, it also might be worth your while to have a look on facebook, I know someone who found their band on there. You'll definitely get a dj and band for that price, probably even cheaper. Majority of djs I know get paid 100-200 for 4/5 hours work in a nightclub so you should have no problem getting a band for around 1000.
It'd be worth your while offering the band/dj some dinner, my brother did this for his wedding and the band agreed to knock 100 quid off their price.