Presumably, this is to record customer orders to purchase product from you or vendor purchase orders in order for you to purchase product from a vendor. Either way, you need more tables and relationships in order to document the fact that different orders will specify different quantities and thus look up different prices based on the Quantity.
The standard data model (tables/relationships) when you don't have "banded prices", would look like this:
Orders::__pkOrderID = OrderLineItems::_fkOrderID
Products::__pkProductID = OrderLineItems::_fkProductID
This allows you to put a portal to LineItems on an Orders layout where you select Products by ID in the _fkProductID field and info about that Product (including but not limited to pricing) is looked up (copied over) from Products.
To support quantity based pricing, you can link in your Prices table like this
OrderLineItems::_fkProductID = Pricing::_fkProductID AND
OrderLineITems::QtyOrdered > Pricing::Qty
In addition to specifying those match fields, you'd double click the relationship line and use the Relatiionship Details dialog to specfiy that your Pricing records would be sorted by Qty in descending order. That way, the price will be looked up from the pricing record with matching ID that has the Largest Qty that is still less than or equal to the amount ordered.
If your orders are never for more than a single product at at time, you don't need the orders table, but you still need a table to fill the role of OrderLineItems.
For an explanation of the notation that I am using, see the first post of: Common Forum Relationship and Field Notations Explained