Glad to hear that.
If Critical CSS makes a huge difference to ‘perceived’ site loading times and that ranks you higher, and money is no question, then $10 / month is probably a good investment.
If however there are other ‘real’ improvements that can be made such as better server setup ( for faster response times ), reduced network requests (eg. less plugins and 3rd party request ) or smaller file sizes ( eg. better image optimization ) then i would put my time into that.