That's high - the starter is easy to replace with simple hand tools. I'd find your most mechanically inclined friend and have him bring tools and help you do it.

You have to remember that a garage is going to charge you about $100/hour in labor and will have a "minimum" (in other words when it takes them 10 min. to replace your starter they'll charge an hour or more.) From the quote I'd say they're a 2 hour minimum (the diagnosis will likely cost you something whatever way you do it) plus the part cost (which whatever they put on the receipt is going to probably be in reality the same price you'd pay at Napa).

Autozone, Advance and Napa all sell starters at about the same price - $150-ish for the part plus the core deposit. There are "New" and "Remanufactured" types. Since all the functional parts are new in either one, it's up to you if you want a brand new one for a higher price or not. Since you should be getting a lifetime warranty, I'd buy the reman one.
A lot of folks like the Napa parts.
Bear in mind that a battery is also going to run about $150 these days, so if you can replace both of these yourself, you can get a new starter and a new battery for about $300.

 

A lot of folks like the Interstate batteries for a brand. I've never had a problem with the Autozone ones. My Dad always liked the DieHard, but I don't know if they even make those anymore.