Depending on the shop, $800 might not be a bad price. I know of shops that charge that much, but they re-machine the entire cylinder assembly. Does a homeowner need that kind of quality? No way.
Anyhow, sure a machine owner with some mechanical ability can do this. I would go invest in a good quality 3' pipe wrench, not some Harbor freight pos. Do not, absolutely do not boil seals. Most are rated for 212 degrees max. You can heat them, but do not boil them. Always heat them in some kind of fluid, oil or water.
Probably the first thing you want to do is extend the rods all the way out. Now, take your thumb and index finger and grab the rod. Keep your minds out of the gutter now because I'm being serious. Run your hand slowly up and down the rod feeling for anything not perfectly smooth. If you have a beat up rod, no sense in putting a seal in it. And, if they are sister cylinders, absolutely rebuild them both. It's kinda like having bald tires on your car and one goes flat. The other one still holds air but do you just get one? There's more theory behind it, but that's the simplest way to put it.
Post pics and if you run into a snag, just ask.
Andy