You would need some sort of cutter, and some sort of joiner.
What do you have room for?
A Tablesaw with a Mitre Jig, or a well calibrated Mitre Saw don't take up much room.
If you have room for something larger, like a Double Mitre Saw, or 2 Mitre Saws, with a measurement system, I'd go that route.
A V-Nailer, or a Hoffman Thumbnailer also don't take up much room.
A dust collector is also important, and you may also need an air compressor to run some of the equipment.
If you can only get one item, I'd go with the joiner (either type), and order chops. Chops usually cost less, and ship cheaper than joined frames. Also, a cutter withut a joiner will be of no use.
Do you have room to store frame moulding?
Being able to buy by the box is the big cost saver.
There is a bit of math to consider when buying a stick of moulding vs. a chop.
A chop generally costs about 60% of what length costs.
With length you are purchasing an entire stick. Generally 9.5 ft.
It is better to get a chop on anything up to 6 ft, and between 9.5 and 12 ft.
You also have to deal with moulding coming in unexpected lengths, allowances (defects that you don't pay for), knots and damages that you aren't credited for, wood being a different colors on 2 sticks needed for a larger frame.
Then, what do you do with the leftover frame moulding?
Buying by the box gives you greater saving, and allows you to have material on hand for any potential Rush situations.
You'll also have uses for left over stock on the next frame you make.
If you need to rent more space in order to save money, are you really saving money?
I am fully invested in cutting my own frames.
About 40% of our shop is dedicated to storing, cutting, and joining frames.
A 40% rent reduction would be nice, but I find that the ability to Rush a project sets us apart from all of our local competition.