Here in the UK I notice that the price of a 512 Mb card is way more than twice the cost of a 256 Mb card - @£200 and @£60 respectively. Is this normal or just a UK thing.
Entirely normal, each time a memory manufacturer tools up for a larger capacity they recover these tooling costs by making the first movers buy at premium prices.
The highest Capacity Compact Flash (4 gig) and SD (1Gig) are incredibly pricey and down at the "volume" end the prices get more realistic.
The rule is wait until the prices come down they WILL or accept the fact that you need it and pay the premium