It really depends on how much spare cash you have, and what your income is. What one person is happy to pay, another won't be.
DH and I bought a Robert Cook glicee for CAD1800 (tarted up by his hand) a few years ago, whereas his originals sell for about 20k. We probably wouldn't spend more than about £500 on any painting these days.
Thanks for your replies, interesting range really. The reason it cropped up was because a friend has just baught a lovely oil painting for about 300 pounds, I think its pretty nice, and I was browsing the artists web site. It occured to me that I have no idea what the range is for art, no experience and no guide. What you have all said fits pretty much with what I was thinking, and that 300 pounds is actually quite reasonable. If only I had time for a quiet child free wander round an art gallery [cant wait for term to start emoticon].