Busted bearings

I have a GMC Denali my wife took to the dealer to get an estimate on repairs, because the vehicle started making a scraping noise on the left side of the vehicle. My wife was told that the vehicle had busted bearing and it would cost around $1200 to fix the problem. My question is does the identified problem and cost of the repair sound in line.

That depends on how much damage the bearings did when they failed. Ask the dealer to show you what else may have been damaged. It is ok to expect a dealer to explain to the customer why the estimate is so high. A good dealer will gladly explain the charges. Just remember you are paying for a higher markup on the dealer installed parts. But the trade off is factory trained techs and a parts warranty. If in doudt get a second opinion.