I just replaced my tranny oil with Redline MT-90 a few weeks ago.
The cheapest I found it online was $7.95 a bottle at JEG'S. Most places even online charge $11-$13 a bottle.
I don't think many chain auto-parts stores carry it on the shelf but they often carry the fuel system cleaner. I couldn't find it locally so I bought it from JEG's and it arrived in about 3 days after placing the order.