Radar Detector: ~$200 – $700. Get either a Valentine or a Cobra. They're about the cost of one speeding ticket and can help you avoid tickets. (This is not an endorsement of driving too fast of course). Valentine is simple but effective and indicates front or back direction of radar source. Expensive, but no bells and whistles. Cobra has a wide range of products with a wide range of prices. Not directional, but has lots of bells and whistles like learning false positives, traffic-cam alerts through GPS, and connection to a network for crowd-sourced data (think Waze, but for stuff like speed traps). Again, these may be illegal in your area—make sure to check first.
Alternatively, one could focus on driving more slowly and more safely, so as to reduce the risk of dying in an automobile accident. Your life is valuable.
But in certain places the optimal speed to drive at (i.e. minimizing some linear combination of probability of dying, time spent, fuel used, etc.) may exceed the legal speed limit (i.e. maximizing revenue from speed tickets).
Then again, going fast and then braking right before a radar may itself be quite dangerous.
What can I purchase with $100 that will be the best thing I can buy to make my life better?
I've decided to budget some regular money to improving my life each month. I'd like to start with low hanging fruit for obvious reasons - but when I sat down to think of improvements, I found myself thinking of the same old things I'd already been planning to do anyway... and I'd like out of that rut.
Constraints/more info:
Background:
This is a question I recently posed to my local Less Wrong group and we came up with a few good ideas, so I thought I'd share the discussion with the wider community and see what we can come up with. I'll add the list we came up with later on in the comments...
It'd be great to have a repository of low-hanging fruit for things that can be solved with (relatively affordable) amounts of money. I'd personally like to go through the list - look at candidates that sound like they'd be really useful to me and then make a prioritised list of what to work on first.