ArizonaKAT,
From my limited experience, the Walmarts around here sell Singer needles. Singer needles are inconsistent as to quality.
I'd suggest JoAnns and Schmetz needles. I have all kinds of brands we've picked up here and there and I use them all. But when I get serious about what I'm making I use the Schmetz needles.
Also do not loose that needle you took out of the machine. I have a 20 something vintage Newhome Greyhound that needed a new needle. The one it looks just like a 15x1 but it's a 1/4" longer. A 20x1 works. The original needle still has the Greyhound emblem on it.
Joe