While the in-game shop is available in the WoW Classic client, Blizzard does not have the ability to disable it for specific servers (such as SoD realms).
Although you raise an interesting point, the ingame tab did say certain restrictions apply before you buy it with the option to peruse the details. If you think you’ve been defrauded due false advertisment you could peruse consumer organisations.
SOD transfers are not available and I already recommended they put a warning inside the game about that. It’s on the site or BNET shop though that you can’t transfer.
If you’ve recently bought the transfer token you can request a refund, either through the automated self refund panel or manual ticket. If it has been too long ago or partially used they may refuse it.
There are also 3 different purchaseable transfers:
Classic Transfer (Excludes Seasonal)
Wrath Transfers soon will become Cataclysm.
Retail Transfers.
The above act independently in their own game versions and cannot be swapped or used in another version. The reason why there are multiple versions is so when they choose to give promotions they can specifically target a version group I think.