For 0.5 dollars per hour (or currently 0.1/hr if you reserve for 24h?) on packet.net you can get access to a dedicated dual-socket Cavium ThunderX server with 128GB RAM and a 250GB SSD. I took it for a few hours and now lang/crystal, lang/mono and some other ports work on aarch64.
Ironically, these two builds have involved long single-threaded compile processes. In the mono case, parallelism had to be disabled for C# compilation to work around a concurrency bug.
At least building things like WebKitGTK+ (to test a one line patch) and Krita felt awesome :D