At the dealer or an independent tire shop?

Yesterday, I noticed a "wap-wap-wap" noise along my right side and I could tell that maybe there was something wrong with a tire (maybe a nail)... so when I was at the dealership today to get my weekly car wash, I asked them to check my tires. Lo and behold, the guy comes back and says, "You have one big a.s.s. nail in your right rear tire." Damnit! I just didn't need this freakin' expense right now.... so they proceed to tell me that they can't patch it and it has to be replaced... damn run flat tire would cost about $370, parts & labor.

I asked if I could still drive it a few more days, as long as it's not low on air... since I'd be back in next week anyway for my first oil service (yes, I know the car is only 6 mos. old and already has 15k+ miles on it. ) and she said it wouldn't be recommended.... but I nixed the work anyway and left... I then called my independent tire shop that I've used for years and he quoted the same tire with labor for only $275.

Was I crazy to risk driving with this nail for another day, just to save $100? p.s. I tried to stay off the freeways, and tried to stay under 75 mph.