Not just commercially, but among parishioners, skills certainly do exist. For example, the FSSP church in Phoenix—an ex-Baptist, Catholicized church—was renovated in large part by a good fraction of artistic parishioners.
Before renovation:

After renovation:

(
images courtesy NLM)
All the painting and wallpapering in the sanctuary was done by artistic parishioners. The St. Mary and Joseph status were sculpted and painted by a single parishioner. The tabernacle was built by the priest. The "marble" is really wood that parishioners painted to look like marble. The arch, which has the words of the
Mater Misericordiæ prayer (partially seen in the image above), was traced by using an overhead projector and painstakingly painted by a few parishioners.
This all took less than a year. It really shows what can be done with parishioner involvement and not just some "firms."