There's a new pollos al carbon place on Anderson Mill Road in the same shopping center as Taqueria Zacatlan (same space even). I'm not sure of the name as it was unclear, but they have a large banner outside advertising the chicken.
I picked up a whole chicken the other night and it was very good. Came with usual sides. Maybe not as much seasoning on the outside as El Regio, but very tasty. I got some extra queso so I'm not completely sure on the price, but it was somewhere around $15 for the whole chicken.