I have my DRs with TPMS. In retrospect, they are not needed and it was a waste of money.
Consider that at the drag strip you reduce the tire pressure. The pressure is reduced to where a mil will trigger. So why have them?
Now if you drive the DRs on the street, I can see where it would make sense.
Regarding if the car will run right: The car will run fine without them but you will get a notofcation in the DIC (driver instrument cluster) that you have an issue with the tire pressure monipr system. If memory serves me it states that it needs servicing.
Regarding best place to buy them: you can google them on ebay or buy them from dealer. I bought mine from dealer and had them installed.
Note: In order to synch them to your car, you will need to refer to your vehicle operators manual. The process is outlined there.