Hard drives are getting cheaper. It's like a rule or something.
When I first built my system I added one fast 74gb drive for the OS and one 500gb drive for storage. That 500gb drive cost me about $110. I later added another 500gb drive for about $95 and then even later added a 500gb external drive for about $120 (yes, I currently have over 1.5tb of storage - though 500gb is strictly backup).
There are currently 1tb hard drives (1tb = 1024gb, 1gb = 1024mb) on Newegg.com for as little as $95. Sick. They go up from there, but even that is a damn good price.
And then there was one... Hitachi has a 1tb hard drive on Newegg for $110 but with a $30 MIR... for you mathematically challenged folks, that's about $80 after rebate. Crazy cheap, for 1tb.
But wait, there's more!
Order now through live.com's cashback program and you can save an additional $3!
That may not sound like much, but when I can say that I bought a 1tb hard drive for under $80 (shipped, no tax), that is awesome.
For me, anyway.