Well had my first nail removed from my rear tire on the passenger side....
The cost to repair from the inside of the tire was only $39.00 (usd), which was much better than having to buy a new tire as my tires only have 1800 miles on them.
Thankfully it was in an area that you could repair and an inside patch is leaps and bounds better than an outside plug! That tire is essentially new again with that patch.
A few mongths ago I had three nails within a week in my rear tires. Don't ask me how. Except for the community I live in, all my driving at that time was highway. Two of the nail punctures were repairable but the third was not and I had to buy a new rear tire. However it seems that tire manufactures are now recommending both an internal patch and an external plug.