You say any of the ACA's are cheap enough! I think that's part of the problem here. Peoples perception of what's affordable. I personally haven't got £145 for an ACA1230.
I would like some extra ram but (and yes, that example I posted is OTT) you don't see many options available at an affordable price these days.
The ACA1221 is reasonably affordable to me with the potential to unlock it later. That's the attraction for me.