Got a Motorola FX 7400-4 UHF reader on Ebay for about $75. There was no 24V power supply with it so that was another $46 on Ebay. They have more readers and power supplies. To use with it for $50 got a circular, gain > 6db, RP-TNC connector, rated IP54 (deficient in a downpour) antenna. Good antenna will be more like $140. Then a 15' LMR200 RP-TNC connector, low loss cable for about $35.
Motorola has a quirky demo program "Session One" that records tags read in order of first read. I had tags in another room 15' away and it was getting them sometimes. So for $206, I have a, pseudo anyway, chip timing system.
Have not tried it out at a race yet but the used FX7400 is a neat little gizmo and the supply is limited. If you time, you might want to consider it for a back up. To be a great labor saver, all it has to do is record almost all the tags in a 100 person 5K. Then, between finishers, I can manually enter them into my results program. Custom race timing software is available from Brian Agee.