Shopify bundle

I need someone experienced with Shopify. Shopify does not offer selling the product as bundle. I need to add this functionality. Example: I have 1 T-shirt, in 4 colors, and customers can choose if they want to buy it with a hat. So two separate product with prices T- 20$, hat - $10, bundle $25 so the variants are: T-shirt, white, without hat - $20 T-shirt, white, with hat - $25 T-shirt, blue, without hat - $20 .. .etc Then, when buying the bundle, Shopify must check whether qty for both products is >0. After ordering, the inventory must be decreased for both items (inventory tracking) My shop is running already so this functionality would have to be tested on some testing account, not my production account. Let me know if that is possible and what price would it cost.