I've had no problems with marking a gift as a gift.
Alternatively you could write a value of 5$ on the package. That will also do the trick.
I recently bought a part and had it shipped from the US. I paid $29.99 (23 euros) including US VAT. It was advertised as such on the customs declaration.
According to the paperwork, Belgian customs had put a 17 euro import tax + VAT on it, and FedEx added a 10 euro fee because they had to advance that money to get the item through customs.
That's more taxes and expenses than the item itself was worth.
So yes, either label it as gift or write on the customs declaration that the items in the package are 2nd hand and old, or that you're shipping it for repairs.
They may let it go through that way.