The Gens Ace come and go in stock at hobbypartz. You just have to look for them and buy them when they have them.
They have these two in stock, if you could make some combination of them fit in your vehicles:
http://www.hobbypartz.com/98p-60c-4800-3s1p-3333.html
http://www.hobbypartz.com/98p-60c-4800-4s1p-4444.html
I've had good results with the Gens Ace packs.