Angela Marsh wrote:
Does anyone sell an inexpensive fertilizer injector for in the line of a
sprinkler system? Something that can be soldered into the copper pipe
coming out of the wall, won't leak, and will siphon up fertilizer-water
mixture from a closed bucket?

I bought a hose bib injector that was pretty cheap, made by EZ-Flo.
See them he

http://www.ezfloinjection.com/1-6.asp

Ezflo manufactures a boatload of different injectors, and sells through
quite a number of distributors, viewable on their Home page.