Ideas: In mission shop

Did any chickens hunters felt that coins gathered in the battle are useless ?
it just giving points ,and we cant do anything after collect them
Did anyone feel that 36 slots of equipments are insufficient for battle?
So, I suggest that IA should add a new in-game market ,and all items are purchased by coins
-The shop is only appear when we reached Wave 30 .It does not appear at short or trivial or easy mission
-The shop suppy us with 3 slots of items ,and the items being randomized between (mines ,missiles ,life ,DMG amlifier ,dimesional -phrase out …) with a price of 150 coins for each bundle (3 similar items per a bundle)
-And at the end of the battle , the remaining coins will be converted to keys (50 coins per a key)
-The big coins (we collected 3 of them while defeat random chicken)=3 coins
-the intermediate coins (gathered from chests , eggs ,bosses)= 2coins
The shop is solution for the wasting of coins(sorry for my bad english)