With the new proposal to max cards to get the maximum rewards per league about to be passed, I listed some possible teams I can build for silver and gold league, this means a maxed silver team. Here's a maxed silver Fire deck for you to consider.
I avoided epic CL cards since they are too expensive to max out, same cost as a maxed legendary. I would like to point out that Gargoya Lion is a good tank at level 5 with 6 mana, Flying and Void. It's great at low mana battles.
You can reduce the price by bidding from the market. Also, you can opt not to buy some of the cards like Xenith Monk. You may also choose just to rent certain cards so the total price can be reduced to less than $100.