$5/month, 500 errors/day
You wanted a cheaper plan, so we created one! For only $5/month you find out about upto 500 JS errors everyday that your users encounter on your site! It doesn't get much cheaper than this.
Just because it's cheaper, don't think that it's worse. You get all the features of the more expensive plans — high performance fail-safe error tracking, powerful grouping and aggregation to keep the noise low, flexible filters to let you slice and dice your errors, and above all, peace of mind knowing that you aren't in the dark about errors your users encounter.