Free Australia Shipping except when shipping costs over X amount

[robck]

Hi there,

I'm looking for recommendations on shopify apps to support these requirements:

• Calculate shipping cost at checkout based on the customers address/post code, ideally using Australian post, or boarder express 
• Shipping calculation must be based on dimensions of product boxes and weight. There will always be 1 product per box.
• If shipping calculation is under X amount, display to customer "free shipping" 
• If shipping calculation is over X amount, add the overage to the order as the shipping cost (total shipping cost minus X)

For example, if we set X as $40 

• Customer orders 1 product for $200
• Customer checks out and enters their address 
• Shipping is calculated with Australian post and costs $60 (customer doesn't see this)
• Customer is displayed $20 for shipping ($60 - $40) 
• Customer completes checkout with a payment $220 

Hope this makes sense. Are there any apps other there that do this for Australia?

Thanks