It's apparently being discontinued by Garmin, replaced by the 650. So, prices in the $170-200 range should be possible.
From what I have read, it would boil down to whether you like a touchscreen... or buttons... like my unit in the GPSMAP 62 series (also being discontinued and also in the $200 range -- 64 series on its way). Otherwise, I believe their capabilities are very similar. Other forums (
Groundspeak is a good one) have a large number of members asking for a direct comparison between these two units, and are easily found with a google of "compare garmin gpsmap 62 and oregon 450."