I’ve looked into this, and just never found a set that would be convenient (portable) enough for me to use with any regularity.
The Options for wireless ones are as follows:
1. Brower Timing – Start and Stop laser tripped timing. These appear a little more expensive, but I understand them to be very good.
2. SPARQ has a really simple, small set-up – that is pretty affordable. I just haven’t been able to find any of them for sale anywhere online
3. Freelap – Looks like a similar model to SPARQ set up
4. Speed Trap II – Not sure who the maker is.
5. Look around for Skateboard and Ski timing systems – there are options for both of these that could be feasible.