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.
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.