I have a Senco SFW10, about $125, for doing upholstery. When in school, other students, who were not going to professionally work in upholstery, used the Harbor Freight models and they worked just fine. It's the cheap staples you have to be careful of.
With regard to the replacement straps: You may want to consider replacing the straps with jute webbing - a 3-1/2" wide, thick burlap type weave band, specifically for spring and other base support on many kinds of furniture. I'm not familiar with rubber or leather strap supports. I have seen narrow elastic type supports, but not for spring or base type supporting.
Jute Webbing: Staple one end, with a 3/4" to 1" tag extending past the staple line. Fold the tag over the initial staple line and staple the tag on top of the initial staple line. Tighten, very tight, the strap across the furniture bottom and staple the other end. Cut the webbing, leaving another tag, then fold this tag back over itself and staple again. Weave the straps, over and under successive crossing straps, as you install them. Tighten the webbing almost as tight as you can, when installing them, but don't break the woodwork. Often times, jute webbing is installed with the strips pretty much adjacent to one another..... the weaving of the strips may dictate a need for spacing them a little, up to 1" spacing. If you have any coil springs involved in the re-installation, use hog ringers to attach the springs to the webbing.... at least 3, preferrably 4, points of attachment per spring. If you don't have hog ringers readily available, twist tie (on the spring side of the webbing) with a large paper clip and snip off the excess end tags.
Jute webbing may be purchased at your local fabric shop. Dust cover, if applicable, may be purchased, there, too. Blue stripped jute webbing is for backrest support and red stripped is for seat support.
Sonny