£400 each isn't a bad budget and would get you somewhere quite nice in the Greek Islands. Check out the Portland Direct website (booked with them a few times, usually the cheapest) to get an idea of what you can get for your money if you book now. In my experience of leaving it until the last minute you don't save an awful lot and have far less choice of places to go.

what about turkey, it has everything you want, hot weather, gorgeous beaches, good bars etc and lots of different resorts depending how busy you want it or not. 1 of my daughters are 20 and she loves most of the places shes visited in turkey, icmeler might suit you, you also have marmaris within 3 miles so if you want a busier nightlife you can pop over there for the evening too. we love olu deniz but it might be a bit low key for you but hisaranu 5 mins away is busier, have a read up on turkey and see what you think, the people are lovely and eating drinking out etc will be cheaper than most spanish resorts

this company usually do good prices and ive used them before, portland too are good, or doing a diy can work out a good price, we often do diy to turkey

http://www.h4u.co.uk/

How about protarus in Cyprus???