Last week you could have picked up (from acmetools.com) a DeWalt 20v set of drill, impact driver, circular saw, recip, grinder, flashlight, 2Ah batteries (and a radio, FWIW,) for US$399. Nice kit. You'd probably want to pick up some more 5Ah batteries.
As of this writing, that deal is still on.
DeWalt 12v and 14v is 1990's technology.
BTW, I haven't had any problems with the DeWalt 20v batteries, of which I have a bunch, and they get a lot of use. Some people have reported issues with the Milwaukee 18v 9ah battery, but I have a couple and they've been fine. I use them for my string trimmer, edger, pole chain saw, etc.