Well, they come with the default amount of 1GB. Also the new ones support 4GB whereas the old ones only support 3GB. This is because the new ones have the Santa Rosa chipset.
You would order the machine with no extras and then buy either 2GB or 4GB of Ram and you’d just remove the two 512MB chips. If you get a machine that supports only 3GB, you still put 4GB in it but it only uses 3.
It’s not like Windows where you have to re-register your OS if you change your Ram. But yeah their 4GB Ram prices are completely ridiculous.
4GB in the iMac is $850 from Apple but from Crucial it is $150.
The 15" one with the 7200 rpm drive is closer in spec. It’s still $2699, which is pretty high. The problem they have is they don’t change their prices until a product refresh so towards the end of their product cycle, their machines look pretty expensive. Penryn is coming in January so they might become more competitive then.
Even so, people always like to compare Apple’s prices to the cheapest PC they can find. If you compare them with Sony, they are fairly comparable so saying you’d never by a Mac because of price is equivalent to saying you’d never buy a Sony, which I highly doubt is the case.