The OP's link indicates its refurbished but with a 1 year manufaturer's warranty which is standard for Garmin. I think it is a good deal even for a refurbished model but I'd check some online retailers to compare.
I don't believe it needs any unlock codes. I just got a Garmin Oregon 400c touchscreen for $299 with every US coastal chart (as far as I can tell) preloaded. But don't believe me check with Garmin.
I think the pronary difference betwen the Oregon and Colorodo series is touch screen vs pinwheel.