I use pump sprayers all of the time to spray my cattle with fly spray.. I buy them either at TSC or at Home Depot any time I need one, and don't even know what brand they are.
I do two things that I believe extend the life of the sprayers.
1. I always hold the tank upside down and release the residual pressure from the tank THROUGH the wand by squeezing the trigger until all of the pressure has been released. I've never had a wand freeze up on me.
2. I pour a little bit of Wesson cooking oil down the stem of the plunger that is pumped to build up pressure within the tank. The Wesson oil doesn't harm the rubber disk on the plunger, and makes the whole operation easier to use.
Good luck with your new sprayer.
Tom in TN