High performance line from Crucial. M500 will continue to be available and the M550 is merely a higher performing option at slightly higher price
Cheapest price so far for 512GB&1TB. 512GB seems to be the sweet spot.
1TB is US$437 if you want to go bigger.
Not bad for the price, as I stated before, if world war 3 or financial collapse don't arrive by end of this year, the ssd prices would be stable at 250 for 500gb level.