2003 MDX Starter
 

My 2003 MDX makes this horrible screeching sound when I start it and the engine is cold. It doesn't seem as bad if the engine is warmed up. I thought maybe it was the alternator belt, which my boyfriend replaced. When that didn't fix it, I had him stick is head under the hood and listen while I started it and he pinpointed the noise to the area where the starter is located. My mechanic is quoting me $400 to fix it and he said it was because the part is expensive. I looked around online and saw new starters as low as $85 going on up to rebuilt starters going for $399. Why is there such a huge price difference in starters and, more importantly, am I going to be sorry if I buy something on the cheaper end? Also, is it hard to replace? I watched a YouTube video and it seems pretty straightforward.