As title says above, this tool provided by google will help one analyze to see which keywords bring in high cpc.
https://adwords.google.com/select/TrafficEstimatorSandbox
As for proxies, the best keyword appears to be unfilter which pays about $3.35 - $4.48 per click for traffic coming from Australia, UK and US.
2nd highest is the keyword bypass which brings about $1.94 - $2.88 per click.
Enjoy the useful tool!