It just depends really (on what you are willing to pay). But I've seen 4" ones for £60 - so guess it depends on what the shop can get them for and perhaps also how many losses they've had in the shimpment. Some might bump up the prices of those still for sale to make up for the DOA's.
But then again, if it's a stunning specimen, I might!
Do remember that they also get a lot lot darker as they age - and do not stay that lovely bright light silver.