We're even seeing a small hard drive pricing war as companies compete to eliminate stock of 500gb-2tb hard drives and this has helped pricing.. 750gb drives are as low as $40 while 2tb are as low as $99 (after rebates) so I can't see a 3tb drive costing (in the slower green edition) being more than $199 msrp initially and possibly le$$.
There are loads of smaller hard drives (special purpose) .. such as for game consoles. Once hard drive makers get to 1tb as entry level for 3.5" and 500gb as entry level for 2.5" the console market will have to be upgraded to the lowest point of the scale (doubling the 250gb entry level capacity).
If this good pricing keeps up I just might buy a larger hard drive first before blu-ray drives are cheap enough to do volume data backups... Do you know how much of a pain it is to backup multi-terabyte drives at 4.7 or 8.5gb at a time?
Also, as it is.. the curent crop of 2tb drives are designed to "work better" in 64 bit o/s however there are some people complaining about the green drives when used under linux and/or raid configuration (which lead to premature drive failure and/or wear & tear). Therfore the buyer must educate themselves about which drive is appropriate for their needs. Not as complicated as buying ram.. but close enough.