Will your solution be as well tested and engineered?
Sun doesn't do much engineering here. Grab a bunch of SATA drives engineered by someone else, put them on a SATA chipset engineered by someone else, skip adding RAID to cut engineering costs and you have a storage array. Someone in China crimps the cables and packs it in a box, one metal and then one cardboard.
But I could go to my local PC enthusiast store buy a pair of 800W or 1200W power supplies, a mobo with quad core, 8GB of RAM, 6 SATA ports built in, 2 x 12 port SATA add ons, 30 1.5TB Seagate drives. Then load Linux (or Solaris) for 45TB of the good stuff and RAID it the way you want. Cost, a fraction of Sun box per TB. BTW, 1.5TB of Seagate SATA is under $200 right now. I am sure I would get a discount if I said I wanted weekly orders of 300 to build 10 per week. Oh, add 2 x 1000BT for bonded Ethernet, need that I/O.
For just 2TB, you really only need 3 1.5TB Seagate drives, use on board ICH9R or ICR19R RAID 5, on the cheap. Might even be able to do that for not much more than $1000 with 8GB of RAM cache. Ooops, Solaris doesn't support many ICH9 configs, use Linux.