In most I have owned you could get a less expensive Valet key which basically allows someone to enter your car through the drivers door and limits them to something like 30kph.
It doesn't give them access to the trunk or any interior compartment.
However the last time I looked these keys were still around $100
I've switched to a Freya Hoffmeister style tether which attaches to the sprayskirt. I've added a loop of 1/8" shock cord (breakable or easy to cut if necessary) to the front of my sprayskirt(s). A line from the bow clips to that loop.