Be careful, it's very addictive. Once you try it and understand how the movements can work to your favour you will want to try even larger formats. I started with a cheap 4x5 monorail, soon moved on to a 4x5 field camera then 5x7 monorail, then 8x10 monorail (everything in the UK is expensive for 8x10 and everything is a whole lot larger too) then settled back to a 5x7 Field Camera with an additional 4x5 back to enable me to use 4x5 too (some film stocks are not available in 5x7).
Fortunately some of the lenses I had bought could be used over all the formats so I still have many of them.
If you do decide to go to 4x5 I have a 90mm Super Angulon spare that you can have cheap to get you started, the Glass is fine as is the shutter but the barrel is quite marked, it is in a 00 sized shutter but has a 00-0 adapter on it to enable it's use in a standard Copal 0 lensboard. This is a good wide angle to get started with and has a decent amount of coverage for movements on 4x5. I can also chuck in some OOD 4x5 film to get you started with.
You can process 4x sheets of 4x5 'Taco Style' in a Paterson Universal Tank but it is a bit of a squash, much better to use a Paterson 3 Spiral Tank for this, if you have a Paterson Orbital Tank, you can process 4x sheets of 4x5 in that too.
Join the
www.largeformatphotography.info/forum it has an amazing amount of experience and talent there and they are very willing to help. They also have a good buy/sell section and you will be able to get some of your stuff there (there is a minimum time and posts for access though so the sooner you join the sooner you can participate if required).
I've just had a look at Peter Walnes website, he has a 4x5 Arca Swiss Monorail for £95, a Copal 0 lensboard is £33 the Arca Swiss wide Angle bellows is £15
Ffordes has a Cambo SC 5x4 Monorail for £149
They have 5x Toyo DDS for £75 (in my opinion the best DDS)
Cambo No1 Lens board £25
150mm Schneider Symmar f5.6 (take off the front element and this is also a 265mm f12 lens, and the front lens alone gives about 300mm 'ish' f12 too both nice portrait lengths on 4x5) for £180
So you can get quite a useful outfit to get started for £150 for all 3 items from Peter Walnes
The Toyo DDS slides and 150 Symmar from Ffordes £255
The 90mm SA/film from me (under £100),
You can get by initially with a cheap Lupe from ebay and a Large Black T-Shirt for a focussing cloth (could also throw in one of these as I am certainly 'large').
So a little over your budget but a quality camera, with 3/4 focal lengths, 5x DDS and a Wide Angle Bellows for about £500 is not at all bad.