NewEgg has this
Seagate BarraCuda ST3000DM008 3TB 64MB Cache SATA 6.0Gb/s 3.5" Hard Drive Bare Drive $79.99 - $10 (promo code: EMCBCBD23 ends 12/13) + Free S/H = $69.99. TBH, I don't know how fast this SATA HDD is, but it should be faster than the 3 TB Seagate SATA HDD that I bought from a local Fry's Electronic store about 6 months ago) is pretty fast (see the hdparm output below) and can be used as a NAS HDD on my Seagate GoFLEX Home.
[root@linux:/home/local/PEOPLE/habibie 20%] # hdparm -tT /dev/sdb
/dev/sdb:
Timing cached reads: 2264 MB in 2.00 seconds = 1131.63 MB/sec
Timing buffered disk reads: 522 MB in 3.01 seconds = 173.40 MB/sec
0.147u+2.729s=0:15.08e(18.9%) TDSavg=0k+0k+0k max=4212k 1084928+0io 0pf+0sw
[root@linux:/home/local/PEOPLE/habibie 21%] #