I start by saying "I don't get in the water for less than $125" then we discuss the other pieces. Time, mileage, fuss...lots of things to factor in.
When running the math, I'd be hard-pressed to do a dive for less.
First, I'd have to load equipment, drive to the dive-shop, fill tanks, drive to the location, lug gear from car to location, put on my gear, dive in unknown conditions and depth, lets assume 2 dives (maybe or maybe-not find the item), load up equipment, drive home, wash off equipment, set it out to dry, shower, then finally put it away.
The only thing that would make a $125 dive worth it, would be if the dive doubled as recreational.
Story time about what not to do: The one time I did an attempted retrieval dive, it was me and my dive-buddy. We drive my buddy's boat and arrived at the dock where a boat-prop had dropped, dropped a line about where the prop fell in, and started the dive. I lost my dive buddy on the way down, and hit bottom at 130ft in 54f water. There was about a 3 to 6 inch layer of silt. My dive-light was almost useless, because it had a narrow beam that was blinding in a tiny spot, and no spill. I found the line we dropped, but didn't see the prop nearby. The short-story is the dive was miserable, we didn't find it, and it was potentially dangerous (especially for me, a newer diver) without a redundant air supply.
My buddy didn't condition payment on whether we found the prop or not. We could have instead went about 1/2 mile away to a party-boat spot and easily found a bunch of sunglasses instead.