It's really bad and ignorant to make a comment that all systems sold right now are 1.51 or higher.
The laws of supply and demand, plus the sheer number of 1.50 out there.. and the relatively new 1.51 + makes for a really mixed market.
In the last two days.. locally.. I picked up a dozen units. Walmart, Best Buy, Future Shop, EB games, etc and a few others. all 1.50
Does that mean everyone else will find 1.50 from these or other shops? no. Sooner or later, 1.5x will be the standard, as old stock is cleared, and new stock arrives. Some shops suffer more from overstock than others. Those shops.. will have 1.50 longer than others.
Friends stateside made the same purchase, in as many major shops.. and got similar results.
1.51 is not "EVERYWHERE" yet.
It's also possible.. that the one you got, is a return that was repackaged. It does happen.