You have to decide what "kind" of gunsmith you are going to be... the type of work dictates the equipment needed. If you are planning on doing a lot of re-finishing work, then you will need different equipment than if you are going to be building high-end 1911's. Custom rifles require an almost completely different set of tools.
For example: If you are doing rebluing you need buffers, bluing tanks, oil bath, hot water bath, parkerization tank and a good set of punches, sandpaper (of varying grits) and files (everything from needle files to drawfiles).
If you are doing 1911's, you need a good mill, proper jigs, maybe a small lathe, and the standard assortment of tools.... and possible refinishing equipment if you don't have a contract with someone to do it for you.
For building a custom rifle, you need a good lathe, band saw, wood mill, drill press, action wrenches, barrel vise, reamers, scrapers (only a few thousandths of wood removed at a time for proper fit), good tool bits, drying stand, files, refinishing equipment if you don't have a contract with someone, sandpaper and lots of cutting fluid (I like kerosene for my reamers).
For all these things you will need a good table, vise, measuring equipment, and a good deal of patience and a love of Cheerios and ramen noodles
So you see, price can vary from about $10K (for the 1911's) to over $80K for custom rifles.... and it could go up even more from there depending on what else you want to do.
So this is not something to take lightly.