There isn't anything cheaper. This is the the cheapest I have found:
http://cgi.ebay.com/Milwaukee-V28-Li...QQcmdZViewItem
They aren't all that expensive compared to the Makitas. The V28 packs have 2 more cells in series, so the costs come out pretty close.
SH Z-Car, Custom Crawler, 8s Savage,
12s XTM XLB 1/7 buggy,
4wd 4-link rear/IFS Pro4 truck,
Custom Hyper 10 Short Course,
Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz