It might be easiest to start by looking at local dry cleaners. Many of them offer alterations and some of them have very good equipment, including industrial machines. Any larger scale local tailoring businesses should also have industrial machines, ...
Wal-Mart for both sewing machines and sergers. They have machines that start out at like $97 and go up from there, they also have sergers that run around $150. They are good brands that do a good job, mostly Singer machines. My only suggestion is to ...
my guess is that most of those types of companies are now gone due to the dominance of Ebay. i would try them first