You should be able to buy a E-Type IRS for well under $1000. The gear set is a Dana 44, Corvette, Camero, Trans Am, and I just had mine rebuilt including gears , bearings, seals and a new U J yoke for $580. If it's a pre 69 figure on sleeving 4 cylinders, $200 Plus UJ and hub bearings. The inner wishbone bearings are needles and hold up fine the outers are tapered rollers and if not set with the proper pre-load they wont last 1000 miles!
The racing shops have replacements in bronze or a nylon type material. If your going to stay under $2500 you must do the assembly & dis-assembly yourself. Time consuming, not not real hard. That's the worst case scenario as these are pretty tough units and you may do nothing but rebuild the brakes and replace the outer wishbone bearings
Good luck, Bob