I did not know about the Harbor Freight 4″ saw. Sounds like a deal to me for someone just starting out. It sounds like if you get a decent blade and it will do the job. I also have the ultra-tec adapter for using a blade on your faceting machine but do not care for it myself. It can be done but not as easy as dedicated trim saw.
Joining a gem club is a great idea I forgot about. The one in my town has a shop with a bunch of different saws including a trim saw. You will have to plan ahead and do all your trimming at the same time.