I just did an AX-5 to AX-15 swap, and while looking found a guy in PA on Ebay who had an BA-10 to AX-15 listed, I called him and told him what I was doing, he knew what I wanted and changed some of the parts around. I think it was 1200-1300 for the complete set up. (Rebuilt transmission and transfer case, bellhousing, etc.) I don't know much about the BA-10 but might be something to look into. The only issue I had was shipping (I'm in AZ) and it took him awhile to get everything out to me, also, he wasn't the best at communicating with me about what was going on, I had to call him a couple times to get information. (He does build them for each order, so keep that in mind as well.) Just figured I'd offer it. Search Ebay for him, I think his website is jeeptransmissions.com
I'm going to get the transmission and everything started on Tuesday, I cannot speak to the quality of his parts yet. I just wanted to add this in case I run into issues later this week. If you'd like, I can update you when all is said and done.