Sorry, no experience with a kit. When I built my garage, I looked online and found a set of plans for a reasonable price. I paid for the slab, bought assembled trusses from a local company, and had Home Depot order me a garage door and header for it. I also had them deliver the materials. Everything else I did myself, except putting the trusses in place and lifting the header into place. This was about 7 or 8 years ago now, but the whole thing was very reasonable (I would guesstimate around <$10k for 24' by 24'). I already had a nail gun, chop saw, and all the other tools I needed. I got a little guff from the inspector about not using earthquake washers on the bolts holding the sill plates to the slab, but passed anyway. Oh, yeah, I did have a book on house building that was very helpful for figuring everything out. Planning was the hardest part. If the materials are good, I don't see any reason why a kit wouldn't provide a lifetime of use.