Given the cash you've paid and your relative lack of experience, go with the LBS plan. But I really don't think it would be a bad idea to learn to do this on your own, if you're so inclined. Watching is a fine idea, as is trying it out yourself on bike you don't have as much invested in. Buy a junker and learn some basic mechanics on it. Make sure it's your size, you can use it as a beater. That way, you can get your learning curve out of the way on something a bit cheaper.

It's really not that hard to do most bike mechanics stuff, headset installation included. Try the threaded rod method, it's easier than the hammer/block of wood path
yet cheaper than a HS press.