Listing- any 3 items from my store for $50. How can I do this?

[brockerstore]

I would like to make a listing where I would sell  any 3 items from my store for $50. How can I do this? 

[jellybirddesigns]

You don't have a store - you just have a regular account.

If you had a store, you could run a promotion/sale that offered $10 off on an order value over $55.00, for example.