(Cheapo) Rebuild transmission vs. remanufactured vs. new?

[RedsoX5]

Ok I am just now getting a transmission fault code on my 121K 2005 4.8is "cherry" exterior/interior TiAg blk/silver blk alcantara M texture that I "stole" for $9216 three weeks ago in Duluth, GA. Got the dreaded "4F85" "ratio monitoring clutch E" as the code. Trans. has been "flairing" occasionally going into fourth? gear from third? in regular non-sport setting mostly. I am reading about bushing failure on Input shaft, etc. Am told needs a "new" transmission by my Indy. UGH! YOU ARE KIDDING RIGHT!

Just got the front struts replaced last week and front sensor re-oriented properly which stopped the negative height reading and the "sagging of the front end" after a few hours and now replacing the air compressor (which I bought NEW for $389 OEM from a German company thru Ebay) tomorrow so suspension should be sorted out soon. Also needed a new battery had a real bad cheapo one that was dying. Invested a little over $2K so far in parts/repairs. Now this!

Anyway I am not totally surprised because of the mileage and the history of the ZF 6HP26 transmission my BEAST has in it but my Indy says transmission needs to be replaced/rebuilt and their BEST GUY referral wants $4900 for a "perfect" rebuilt? or remanu.? tranny with two year warranty PLUS $700 intallation by my guys labor. YIKES! But I called around and a (cheapo I guess) place in Morrow, GA says they will do the rebuild with one year warranty for like $1385 (after the $685 special discount HAHA) plus fluid cost and even tow the X5 in if necessary! I think they are INCLUDING putting the tranny BACK in as well!

Ok what gives? Lots of transmission places around and I know they all want my $$$$ but the range is amazing! Also a place in LA is giving me a quote tomorrow which includes me trading my trans. in (core exchange deal).

Obviously I will be investigating this in much detail again tomorrow but just want suggestions on how to proceed. I have NO desire to spend a ton of money on the transmission now I am wanting to keep all costs under $14K and am at about $12K with tax currently. So much for the GREAT DEAL I got! LOL!

Suggestions? Thanks very much!