Personally, I'd be cautious about either, if they were CAI builds. That $549 Saiga conversion is also a CAI build - I've had too many bad experiences with their "built" products (though most of my milsurp straight imports seem to have a CAI import mark, and they are good for that).
The Saiga I picked up from K-var a few years ago ($525, as noted earlier) is a extremely well put together little rifle, and surprisingly accurate for an AK. My ROMAKS from over a decade 1/2 ago are a little less so, but rock solid. I went through 2 WASRs, and gave up (don't get me started on CETMEs and C93s).
Then picked I up a Romy G build by Citizens Armory in MO (on a NoDak receiver) - very pleased with it overall, though I felt like I overpaid shortly thereafter (it was in the frenzy of the last election), but still well under todays AK pricing.
Anyways, if you look at the Arsenal SGL pricing, they have fluctuated wildy - running up in the $800s before the last election, then plummeting to the $500s after the election, then back up, then back down briefly, then up again (way up now). Perhaps after the election they will drop again? I'd take that risk over dropping 5 bills on a Century build right now, but there may not be many other options right now under the $600 mark for an AK variant if you really need/want one.