So how hard is it to install an aftermarket remote start on my 2012 Pathy? Or should I just let a pro shop install it? Anyone install one on there own?

Personally, I advise people not to install them. They may be convenient, but can lead to problems down the road. If you have problems with starting down the road, usually the first recommendation by the shop will be to remove the aftermarket system. Shops will usually not have wiring diagrams for the system or diagnostic procedures and if the company goes out of business, it makes it practically impossible to get the information unless you keep all of the paperwork and manuals that come with the system. The systems typically use one of your programmed keys stored inside a box under the driver's side of the dash to be recognized by the security immobilizer system, which can make sure vehicle easier for thieves to steal. I would only recommend a remote start system if it was available from the vehicle's manufacturer.
If you choose to not listen to my advice, then who installs the system is a question of your ability and equipment to do so. Often companies make their installation instructions available online for download, so you may want to check and see if it's something you are comfortable doing. If it is plug and play and you have basic mechanical skills, you should be fine. If the kit uses Scotch splice or tap connections to splice into the vehicle's wiring, I would rather that the wires be soldered and appropriately insulated to prevent future problems. Connectors that splice into the harness can develop poor contacts over time or weaken the integrity of the circuit as it cuts into the wire.

Thanks for the advice SMJ.. I will look into it not quite sure what way I will go.

I used the Smart Start system from Viper. They don't have an extra key under your dash per se, but there are a lot of electrical components needed for the job and a significant amount of knowledge is needed to do the wiring. Best bet is to take it to a professional installer. Myself, I chose Best Buy as it was the most convenient pace to go to, the Smart Start is very expensive and I just put it on my BB card. They may have some young kids there that do the work but at the end of the day the Best Buy Customer Service factor and its convenient locations no matter where I might be at the time service is needed, was the reason I chose to get it done there.

The one thing I did notice is that with the alarm and security features on there is a small draw on the battery - which can lead to a dead battery if you're not careful...