Buy what you can afford to lose. So if that is a refurbished model, then you can maybe find a really great deal at some sites every once in a while. However being sporting devices, they tend to not have a truly great deal very often.
gpscity and
Factoryoutletstore are two that I've found some deals on refurbs occasionally.
Otherwise I tend to buy straight from Garmin's site. And though the latest and greatest does come with flaky software sometimes, it's usually quickly fixed. And I really feel that many of the problems were the interface between the bike saddle and the device. It sometimes just takes a while to understand the way Garmin's work and especially when it comes to new features it seems that it's too easy to misunderstand what it really does and how it works.