I was going to say the same as as porteous has written. £500 is top RRP on a new one. I had a quick look around and there is one on
ebay, buy it now for £375 new. It is a small size and only one left, but it gives a clue to what they are worth. The few second hand ones that I have seen are around the £150 mark
If I was looking to spend £500 on a tourer I would be looking for a second hand Dawes Galaxy, or a Hewitt. Before anyone jumps in and says they have shot up in price for new ones, I know, but you do see them for this price if you are patient enough to wait.