GLM 5.3 Flash is incredibly cheap and imho as good as or better than Sonnet. I used it recently to fix an old server that my family had running serving some websites, and by fix it I mean I got it to log in over ssh, figure out what's running there, copy it out, log in to a brand new droplet on DO, set up a fresh instance of apache with everything patched up to latest, copy that ancient content over, make sure it runs with latest PHP which required several rounds of fixes, optimize the system so it runs on the smallest 512MB droplet, harden the system so that ideally no one ever needs to look at it for another 10 years - it took about an hour, and cost a grand total of 4 american.... _cents_

I use Opus at work since we have a nearly unlimited AI budget, but for personal projects I just use GLM 5.3 and I don't see much difference between that and Opus.