lots of info there.
Do you want a 4 speed 5speed or 6speed?
Cheapest would be a 4speed. You'll need the proper trans to fit your rear axle ratio (or vice versa). You'll also need the pedals, a clutch kit, flywheel, perhaps a crossmember, Zbar, trans itself, bellhousing, shifter, shifter linkage. Some other things to check that may need to be addressed (depending on whats been done to your car) Trans tunnel, driveshaft, console, seats.
Its not hard to do if you have a factory service manual
If you get into 5 and 6 speeds (which you absolutely don't NEED), the cost goes up and it'll be more work.
My recommendation for a budget install? Assuming a basic smallblock; an M20 with a set of 3.23s to 3.55s.
If you have 3.08s in the back; a 2.88 1st T10 or an M22Z (2.98). These get the mileage everyone wants, with lots of strength and you can use mostly factory parts for the install.