Good tip for Monster Players. I was also having the same issue with the built in market on steemmonsters. It was just so frustrating to lvl up monsters. Takes so much time.
The best solution I found for it is https://monsters.steempeak.com/
The market has some very interesting features,check it out for yourself.
Also, you can save, I think 10% by buying booster packs on smartsteem
You can find more info about how to do it, in their post about it here
https://steemit.com/smartsteem/@smartsteem/buy-steem-monster-packs-and-save-money
Thank you for sharing this alternative. I have not dig into Steempeak yet but happy with the SteemPlus solution.