I bought one of these and it worked great after I switched out the straw for a regular one, but after around 15 uses the bottom blew out of it and it was spraying out of a pinhole in the bottom. If you could also buy the replacement metal canister for the professional model and use that it might be worth it, otherwise I'd avoid this product altogether.
This product could use some work on the way it sprays. You pretty much have to do a pin stream. The mist nozzle is very weak. You would have to be right on top of a bug to hit it with any product if you were using the mist tip. Its fine if you just want to spray a pin stream of pesticide. For professional use, just purchase the Pro version.