Sure, shop around all you want, if it were my bike that money is not excessive, and I'd be surprised if the cost you got from the shop doesn't include install. Prices (and I am sure quality) of that bearing ID are all over the place (I saw it as low as $7). Hopefully your cheaper option holds up over time. It would have been nice to know you already had a source at your LBS, details like that help the people on here trying to help you. Best of luck with your headset.