Shop offers are never a good deal. My family buys emblems and I buy some others for research purposes ( 5x 5x 3* mono trainer heroes teams ).
Their pricing is the same as movie theater popcorn, and the economics behind it are the same. People who cannot afford it get cheaper tickets because people who can afford the popcorn subsidies all ticket buyers. Though you cannot sneak your own gems into Empires under your winter coat.
This is a topic about gems and IAP ( still fairly current):
([Opinion, Discussion] Effective IAP gem deals in Empires or Return On Investment)
and HotM chasing
(How much should I spend?- HotM cost, and odds, analysis)
or