We have a vendor that gives us special pricing for the amount we buy, so like Qty 1 - 11 = $100/per, Qty 12 - 23 = $90, etc. We are able to do this on the sales side with quantity pricing, but I haven't been able to find something similar for the purchasing/vendor side. Is there a quantity pricing for purchase pricing, or would this need to be done a different way/customized?

In the Vendor record, there's a subtab that will allow you to upload quantity-based pricing

I think the Purchase Contract or Blanket PO is the one you are looking for (I forgot which one of the two). But either way, you need to subscribe to the Advance Procurement module, which I think still sucks

Can be achieved with Purchase Contracts. Although it only automatically uses the contract if using the order items screen. If manually entering a PO then you need to select the purchase contract.