So how good it's performance with single port eSATA enclosures?
Going to need a significant amount of storage soon. eSATA it's significantly cheaper than a SAS enclosure + card.
I had thought that if i'm going to use a snapraid setup for these drives (to make it so only one drive it's active for any given opperation, it should work the same.
What are you asking about? Are you looking to use SAS drives through eSATA? While SAS drives support connection though SATA, your controller needs to be SAS compatible. You can't just use any SATA enclosure with eSATA or USB.
Standalone external SAS enclosures are expensive is because of lack of supply and demand. A klunge may be to use an internal multi-drive 5.25" bay dock and use it outside your PC case, running the SAS/SATA and power cables out the back of your PC. I tried this with a 4 bay dock that happens to support SAS drives and has SATA only connectors on the back. I'm not sure if it was the dock or the cables, but it only worked intermittently. If the drives were connected directly with SAS cables, they were fine.
So the idea that there's no demand for this just can not be true, since people are literally making the hardware, just not the piece of metal to wrap around the drive cage so you can set it on a desk.