Don't ship anything to Brazil with USPS if you sold it through eBay, Reverb, or with PayPal.
Even Priority Mail can and will be held up in customs for upwards of a month and you'd likely have some kind of buyer protection case brought against you for item not received. Tracking also doesn't work once it hits customs.
Any other carrier would be preferable, but obviously very expensive. I just don't ship to Brazil for this reason.