Is there a way I can control which shipping options are presented based on the shipping costs of FedEx.

Normally we only offer FedEx for International. Shipping averages around $23. However for some destinations, the shipping can be $50-70. For FedEx costs > $40, I would like the USPS first Class option to appear with the FedEx option. For FedEx costs < $40, only the FedEx option should appear.

The reason for this is that USPS FC international is slow and unreliable and we want to avoid it unless the FedEx cost is simply too high.