I am the sucker in this story. And that's on me. I should have done more research and shopped around.
But when Sierra Air quoted a cost of nearly $800 to install a blower in my fireplace, I thought "Wow, this must be a huge project. They must plan to tear apart my fireplace and install some big complicated blower system." So imagine my dismay when the service guy unboxed a tiny little fan ($25.99 on Amazon, though I was told that SA pays $175ish for theirs,) and he proceeded to spend quite some time studying the illustrated directions that came with the fan. Then he wiggled the part around until it fit into the space and drove in a couple of screws. No wiring needed. Done. I'm in a wheelchair and could not have done this myself, but an eighth grader with a drill and a screwdriver could have accomplished it. A $781 job?!