As you have probably noticed, decanters can be as inexpensive as $20 or can be $500+ for some of the elaborate Riedel decanters. So does one work better than the other? The straight answer is no... with a twist. Just because a decanter is made with more crystal, or is hand/mouth blown, does not mean that it will allow the wine to open up any faster nor will it improve the quality of the wine. For the most part the price of decanters is in correlation with the amount of crystal (and quality of crystal) that is being used as well as how specialized and labor intensive the process is to produce. Glass decanters that are mass manufactured are certainly going to be less expensive than a pure crystal decanter that is hand crafted by one individual. The more expensive decanters are often times considered a decorative show piece for a curio or cabinet as well as a vessel to allow wine to breathe.
However, many of these more expensive decanters are bigger and allow the wine to flow along a larger surface area when poured out of the bottle. In that sense, they will work better as they allow more air to get to the wine in a shorter amount of time. However it has less to do with the price tag and the quality than it does the sheer size and turns that the decanter makes allowing the wine to aerate.