I got a standard 2.5 tdi window van in great nick with 5 seats for £4400 that had only 44000 miles on the clock! so I am sure you will be able to find what you are looking for, beware of people asking loads for a tarted up dog of a van with millions of miles though (t4's can handle their miles well with good servicing, but it still affects value obviously)
Some have said garages are a good place to buy as they go off book prices, which can be lower than what many are prepared to pay on ebay and the like, due to the t4's desireability.
Am sure you will find a really nice van for the money you have and probably can get a good t5 for that money, just keep looking T:
I suggest, wait and wait, the right one will come along, sooner or later. I waited for about 2 months, looking on ebay and the like, mine came up and I purchased the day after it was put on ebay. As I say, wait for the right one, dont regret buying the wrong van for the sake of a week or three.
Look forward to seeing what you buy in the future.