Welcome to X-Cart forums and thank you for your question!
Did you try to create user-defined shipping method that would be named 'To Be Determined' and would cost 0? Would such approach work for you?
Originally Posted by SiRiC1881
I ship from outside of the US and Canada, so my shipping cost will vary depending on weight, dimension of final shipping box, etc. Because of this, I do not want to lock into a freight cost at checkout as I have to get a quote from the shipper which I will pass on to the customer later.
Is there a way to avoid adding shipping and just putting it as TBD?