It is not that complicated, and Paypal will let you print mailing labels directly. All you need to know is the HS Tariff code for your product and get some free plastic envelopes from the post office. I just checked a 8oz tube to Australia via USPS and it was $7.32. If you added a $10 international charge, that would cover any extra work or shipping. I ship products globally every week and it is very easy once you spend 10 minutes learning what needs to be done.
Also, you state that you are only mailing it to the 48 contiguous states. The USPS doesn't charge extra for Hawaii or Alaska (or military bases) so why would you exclude them?