I don't think I said a computer will run 60 FPS in Dalaran.
I know some people get that in some areas of Dal.

But the particle density sucks there, and you frequently get 20-30 FPS, even with very top-end systems.
Wintergrasp can also slow you down, from the sheer number of people all over the place.

But pretty much, every where else.
Any of the newer systems (i7 based or the AMD equivalent), should do well.

I'm running:

i7, 920 (stock speed)
12GB, 1600mhz ram (DDR3)
Asus P6T (x58) motherboard
GTX 275 (896 mb)
150GB Raptor (less then 50% full).

I have IS Boxer set to cap my FPS at 60 on the main screen and 30 on the slaves.
I get those FPS, pretty much everywhere except Dal/WG.

I have a Patriot Torq SSD on my Christmas list; retails about 250 (CDN$).
Patriot Torqx PFZ64GS25SSDR 64GB, Sata II, Internal SSD

Just searching on Newegg.com, you can get an idea of what is available.
http://www.newegg.com/Product/Produc...0%20-%20%24200
41 SSD's in the $100 to $200 range.