Garmin GLO2 is the cheapest one that I can recommend at the moment. Built-in GPS can be used with RaceChrono, but the data quality is nowhere as good as GLO2. Both have good lap timing accuracy (when installed properly in with view to sky), but GLO2 produces nice trace to judge braking points etc. Also RaceChrono does not do 0-100.
Just found a russian GPS+GLONASS Box that can do timing PLUS server as an external GPS (@16hz) for Racechrono. Wont say it's name so that you wont think I"m making adds. It's cheaper than GLO2 and more functional.
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https://buy.garmin.com/en-US/US/p/645104/pn/010-02184-01
But it would give only 7-8hz and still cost 100 usd. For 150 I'd get the dragy...