I've used the Liquitex Spray colours before, once, they had free samples when they first came out.
They dry a little more glossy than I'
de liked, and were a little easy to spray too thickly. But if careful work well enough.
Alternatives might be Montana spray colours,
http://www.artdiscount.co.uk/paints-mediums/spray-paint/montana-gold-spray-cans-400ml.html
(204 matte colours, with replaceable, interchangable tip sizes, and probably an accessory for mixing cans - theyre aimed at graffiti / art sort of usage I think)
Halfords do a few, just have to avoid the glossy ones (which is most of them) They have a set of 4 camouflage colours in ultramatt to make a standard cammo. And a handful of bright colours named ArtFX (I think)
Can vouch for ken bromley art supplies, and artdiscount

both are my favourite suppliers I've spent hundreds and hundreds of pounds with both companies in my time.
They stock handy brushes and brush soap too
And oil colours for washes, pallets, mediums.. quite a lot of what we might need to use now and then at a good price