Just another thought. This idea will vary with guys who do and do not like to do upholstery work. I loved engine, carb and body work, but hated electrical and upholstery, so I stayed away from them at all costs.
When I discovered that my headrests had gone soft and the powder that I kept vacuuming from the floor was not dust, but rather crumbled padding from the headrests and seats. I priced the various padding kits at the big 3 and went to a local upholstery shop for an estimate. I also took into consideration that if I ripped or tore the chestnut upholstery in my car taking the covers on or off, that getting a match would be tough, if not impossible.
In the end, I was able to pay a local $150 for the complete job, including all new padding and the headrests rebuilt, as long as I carried the seats in and carried them out. That was cheaper than the kit and they came out perfect. All seams are perfectly aligned and the padding is in all of the right spots in the correct amount for that area.
But if you want to do your own, that's fine as well. Maybe the price at a local shop for you will be less than the kit like mine was. That's a hard deal to pass up if you're lazy like me.