I don't even have 80 gems. I have been playing 33 days.

I think you're looking at the market in a bit of the wrong way there in terms of cost. Long term if you're planning on finishing fusions without constantly using all of your shards then you're going to want to be able to pick up all the mysteries you can. 

So really, that price is for all of the future resources you're able to pick up, not just a one time thing. This doesn't include the ancients that show up and the artifacts that might be worth buying, however rare that might end up being. 

The mystery shard is 5 000 silver , not 80 gems , thats the price for the increase slots in the market , which could also be 1 of the 6 ancient shard spawn you get in the market monthly .

Mine and market are 2 places where the gems spent on it will be totally worthwhile in the long run . Just hard to see at first!