Based upon some of the reading I've done, which again is very preliminary, the GPS-enabled devices are likely to be the more expensive. One of the problems with GPS systems is they can range from very simple to extremely complex. GPS isn't just GPS; it's a hugely complex field. You have to try to understand what actual GPS technology is being used by the individual manufacturers, because the overall performance can vary markedly, depending on what their implementation looks like.
On February 14th, 2012. See this statement in context.