Take a look around your garage. Add up in your head the value of all your toolboxes, wrenches, screwdrivers, sockets, welders, pipe wrenches, hand drills, etc. Realize that a machine shop requires all these hand tools as a bare bones basic necessity.
On top of a well-stocked set of mechanic's tools add at least $ 1/4 million dollars in machines and tooling for them, plus a heated building, a phone line, 3-phase power of some sort, advertising so you actually know where to find this shop and an experienced machinist who is there from at least 8am until at least 5pm Monday thru Friday ready to take your job at a moment's notice. Now you have a basic machine shop.
On the most basic level, to put things into perspective let's make a comparison. The staple endmill in most machine shops is the 3/4" rougher which costs Between $80 and $300 each depending on brand, material, type, etc. That's about as much as a new Snap-On ratchet. Here's the catch: That endmill has a lifespan measured in hours and it has no warranty. When it is used up it gets thrown in the trash. Imagine throwing all your Snap-On ratchets in the trash at the end of each day and pulling new ones out of your well-stocked tooling cabinet in the morning.
These reasons and more are why it costs money to get things made.
