I have one Zep. It sucks a**.
These are excellent sprayers and are available locally at Super Walmarts. They are Rubber Maid Professional Sprayers, the spray head is identicle to Griots:
These are from AG. They are pretty good, not as good as above:
These are from CG. They use a "chemical resistant" version of the spray head of the one from AG. The spray heads are both made by Tolco. AG now sells these spray heads alone as "chemical resistant". I got 3 of these bottles and sprayers from CG for $13. They are excellent.
CG also sells a foaming spray head that works well with APCs:
Of course you can recycle some stuff to make a very good sprayer. This is the "good" AG spray head on an old alcohol bottle:
These are from AG as well. I has to take it apart to lube the plunger because it got sticky. The bottle is great, the sprayer is a Tolco, not chemical resistant. It's just OK.
These are from Ace Hardware. I like them because they are 16oz minis. They are pretty good
I'm not sure who makes this style of spray head, but they are very good. So, I always re-use them:
So, to recap, I think the best ones are the Rubbermaid (available locally) and the CG chemical resistant.