The thing with collecting these days is prices are so fluid.
Beckett was great 30 years ago when we all sat around waiting for the next monthly magazine to come out then ohhed and ahhed over the prices and many (most??) sellers and buyers took these as gospel. Between that and Card Crazy magazine at least that is how it seemed here in New Zealand.
As I have not purchased a Beckett price guide subscription for over a decade, I may be doing them a disservice, but certainly back then they were not active in updating pricing on older releases such as the Skybox set you mention. So, unfortunately even if you got a Beckett quoted "price" it may be years old — which may or may not reflect current reality.
This is not meant as a shot at Beckett, just a general observation on how pricing in the hobby currently works and that no static pricing service can hope to be completely accurate.
As mentioned if you are looking for prices on the specific cards checking Ebay sales through their site or using sites like 130point are likely your best bet to get a gauge on the current market.
