Understand this about the DGA. They have an established value for just about anything you bring in the country. ANYTHING!!
The tax they charge is based on that established value. PERIOD. No ifs, ands, or buts.
It doesn't matter what you paid for it, or if you have a receipt, or any other kind of proof.
You show up with an item, they say it's worth XXXX, and the taxes are XXXX.
You either pay the taxes, or they keep the item.
Next time you're in the airport, ask to see the area where they keep all the items that have either been left behind, or are waiting for the taxes to be paid.
You'll be amazed. I know I was.