I'm confused, didn't you just say that they said they're out of the stock of the ones with the 1200W PSU? It's nice that they have the SC846 back in stock though, I was afraid I wouldn't be able to purchase another one at a fair price in my life time, lol.
It's interesting that they quoted you 280 for the R900B chassis with SAS2 backplane and rails...they have two auctions for the R900B chassis that are listed for 325 and 345, not sure what the difference is in the listings, and, they both list SAS1 backplane. Make sure you double check the backplane when it comes in.