Pounds, Euros, or Dollars? I'm running in pounds:
A very fast card for that price:
ATI X800XL (£191.17):
If you want a Nvidia card, the closest you can get is a Geforce 6600GT for that price, which is still a very good card (£146.60)
(This one has 256MB RAM too, while other 6600GT's don't:
Make sure you check that you have a PCI-E 16x motherboard though for any of these two cards!