Key less start FOB upgrade

[Knowles Richard]

HELLO TRUCKERS I own a 2013 gmc sierra 2 wd sle ext cab half ton when purchased new, it came with 2 three button key fobs, I would like to update my truck to the four button key fobs so I can remote start my truck, My truck does have the RPO code AP8 inside the glove box, which in reading online that this is needed to do this The gmc parts guy says they can order a kit for $275.00 and install for a total bill of 500.00 smackaroos He also said there could be some reprograming needed but was not certain , I would prefer to do it my self like every thing else, Any body got ideas, or hands on about this, let me know, Thanks KEEP ON TRUCKING