Um. I assume the century old name-tag
wouldn't suffice. A few dollars for 70 tags?
If you're worried about someone cutting it out, you could always sew them in under the shoulder or somewhere they're not immediately obvious (like the collar, which is the first place everyone checks), or double up with both labels and sharpie.
Or yeah, can you not put a lock on your trunk/cupboard or something?
Setting up RFID scanners in doorways seems:
a. A lot of effort
b. Likely to be removed once said thieves work out what that little box is attached to the door-frame.
Any sort of GPS tracking system is going to get expensive multiplied over multiple garments, and passive RFID has the obvious limitations, although with a high-gain antenna I guess you can eek out some extra distance.