Here's what I've used and some feedback...
Walmart garden spray bottle (~$3) - great bottle with dilution marks on the side. Spray head handle has a nice "foamy" cover over it for comfort (foam cover slides out if you don't like it). I've seen several spray head colors so it may be nice to color coordinate with whatever material(s) you're using. (We're all OCD right? :chuckle: ) Excellent spray head, smooth and efficient, goes from stream to mist and fully closed for storage (NO drips for me!). Coincidently, there's an exact bottle made by Rubbermaid in the janitorial section for roughly the same price, but with a black/red spray head.
Zep spray bottle from Home Depot - Exact spray head as the one from Walmart. Blue and yellow in color without the foam cover over the handle.
Griot's spray bottles - Exact spray head as the Zep and Walmart bottles, BUT the big difference is the bottle that's used. While the Griot's bottle is somewhat unique, I did crack it at the threads. I believe this is due to the type of plastic that's used for the bottle. It's clear and somewhat unforgiving. I think with time, it will eventually become brittle and fail, just like it did on mine. (I've seen the exact bottle at my local Orchard Supply & Hardware if you're in Northern California.)
-Mike