A very warm welcome to the possibility of Bongo ownership.
This FAQ on buying a Bongo may be helpful:
http://www.igmaynard.co.uk/bongo/forum/ ... =43&t=7229
Whilst there are a fair number of Bongos around, it is a small number compared with your mainstream hatchback, there are many variations which may be important to you and they are all between 11 and 20 years old. In short it is not going to be like popping into a couple of car dealers and driving a Ford Focus away, all in a weekend.
At that price you will be looking for one that has been in this country already for a while so skip over the importers and concentrate on dealers or private sale. You will be buying an old vehicle (all Bongos are old!!), so to avoid costly disappointment check out their weaknesses or if you are not technically savvy take with you somebody who is. I would do this whether buying from trade or privately.
The right vehicle will be reliable but their increasingly popularity has seen some dodgy vehicles being sold to the unwary. The warning already given about an ebay seller (appearing with many personae, characterised by one day / short auction, non-paypal non refundable deposit) is important and this seller has also been seen on gumtree. There are also many perfectly honourable sellers in and around Bristol!
Budget a few hundred £££ for full service, cam belt change and inspection as soon as you have bought it. (Cost depends on the engine type. ADS, South Bristol will quote - they fix anything Bongo)
I would build a list of characteristics/features that you want in your Bongo and a list of maintenance questions. Then run through this by phone with your selected sellers. By the time you decide to see a Bongo you (and your techie) will know exactly what you are looking for and will keep your actual bongo visits to a minimum.
There are bongo owners in/near Bristol who may also be able to help with specifics. Just ask. You will usually get pretty quick answers.