Our Garrison had an explosion of TIE pilots last year, TIE can be a bit more expensive than a TK, here is a quick breakdown:
1) Hard parts: Helmet, Chest box, Chest & Back pieces - US$500 - $800 depends on which vendor you purchase from
2) Belt, Gloves and Boots: check out Imperial Boots
3) Compad - US$15 (3d-printed locally)
4) Black Flight suit (must) & Officer Hat (optional) - US$180 (Tailored size by Eadu Armory)
You need not to throw cash and don it all at once. Get the soft parts first (2 3 4) and registered as a "TIE Reserve Pilot" with your garrison and start trooping, after that you can slowly build the hard parts and upgrade to a full TIE Pilot.