Wow, all those prices seem high to me. Do the quoted prices include the new indicators or is that all for labor?
I just replaced my rear turn signals a few weeks ago with some shorter ones that I got at Cycle Gear on sale for $9.95. It is not difficult to do this yourself (depending upon your electromechanical skills and what tools you have available), but it is a little more involved than just plug and play.
The stock signals just come unplugged from the wiring harness. The aftermarket signals usually don't use exactly the same size connectors or have exactly the same length of wires, so you should expect that you may need to either tighten up the female connectors or crimp on new male connectors, and possibly splice on a small length of wire if you need some extra length. The rest of it is just unbolting the old, rebolting the new, and ziptying the wires to the subframe.