You could get the Norma brass from bullets.com on closeout, 250 cases for $200. Either have the barrel cut for the Norma dasher chamber or trim the brass back to Lapua chamber length. While I strongly prefer Lapua brass (and it may show back up again here in a month or two) for a wife/backup PRS/coyote gun I wouldn't mind Norma brass.
243AI to me seems like burning a whole lot of powder and eating up a whole lot of barrel life for no good reason, unless you really want a screaming 3400fps coyote gun with varmint bullets.
Velocity difference is probably 2950 vs 3150-3200 with the 105gr bullet, barrel life probably 30-50% less with the 243AI. Way less muzzle blast with a Dasher, you're only burning 32gr of powder vs 45 grain with the 243AI.