The pump up sprayers are going to pretty much be all the same. If your going to be doing decks a lot I would buy a piston pump airless sprayer so your not replacing them often. I have a titan 440i http://www.titantool.com/content/subPages/electricAirless/440i.html they are around $600-$700.00 but they are really good. Graco makes better ones but for staining decks it's probably not needed. It depends what stain you are using but like ReadySeal and BGA do better using a HVLP sprayer. In that case you can rig up a system using a delevan or shurflo pump if you want more information on that let me know.