It's a $1500 option if you tick the box. Admittedly, the $1500 is on top of the Limited upcharge from the SR5, but it's not like the Limited only gets you the option of choosing the power steps. Regardless, the parts needed will probably be in excess of $2000 if you add them up from Toyota's individual parts lists.

I'd wait for the AMP Research version since that will be priced as a kit and include everything you need. I'm on the fence about power steps for durability reasons, but they're very slick in operation. I had them on an Escalade and loved them. I even thought about taking a Tacoma or Tundra one and making it work. My concern is what to do if they seize up from dirt, salt, etc. Would make it nearly impossible for the wife to climb in. I'm not sure if I'd want to deal with that in the middle of winter.