Hi all,
so here is what I found out after a lot of research:
1. all plastic head keys (also called chip keys or transponder keys) must be coded on site with some special coding machine.
2. most locksmiths can do that or site or second option you have to tow your car to the dealership.
3. YOU WONT BELIEVE how much you can negotiate with them, i called a few locksmiths and a few dealerships, and the locksmiths usually wanted to charge less with on site service.
4. here is a great website that helped me a lot, saved me about $150 for the whole process, highly recommended:
All The Information You Need To Know About Getting a New Buick Replacement Key. In Addition, We Offer Fast 24 Hr. On Site Service.
lost-car-keys-replacement.com