Hi Steve,
years ago I was very heavily involved with RFID and one of the leading RFID vendors that I worked with was Alien Technology. I used both their readers and tags and was able to read tags from a few feet away from the readers. We would place 2 antennas at a doorway and be able to read tagged items with no problem at all. The tags were passive tags so as you mentioned inexpensive and do not require anything but an antenna. I'm sure their products are even better today than they were years ago so they may be worth taking a look at
back then I used the "squiggle" tag
https://www.alientechnology.com/products/tags/squiggle/and here are some readers
: https://www.alientechnology.com/products/readers/very cool use case for sure
Keith
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Keith Jusas
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