@hrw Oh, I see. Unfortunately in this talkative age full of promises in the cloud, I'm afraid the only sensible/cheap ARM will be indeed in the cloud.
I'm sure you already know about gcc compile farm project? But, well, the most newest arm there is altra max. (neoverse N1).
https://portal.cfarm.net/machines/list/ -- that's considering you are in open-source development so you do have access to those anyway...