I'd been thinking of buying one, and I think this is going to push me over the edge. Lots of retailers are offering 25% off + $50 rebate from Garmin, May 16-26.
I've found the same deal at a number of retailers (Running Warehouse, REI, and others): $299 + $50 mail in rebate. $250 for the 910xt is fantastic.
I will probably buy from Running Warehouse because they were really helpful when I had issues with my 210 last year.