Simple to reduce or eliminate the VAT. Perfectly "legal" (in quotes).

These are just simple piece of plastic. Their actual "value" is pennies each. Obviously you've priced them reasonably to make up for the costs of the mould and labour, etc...

But who's to say you have to value them on customs forms for the price you're selling?

Sample customs forms:

"Description: Spare plastic button caps"
"Declared value: $1.00"

Done.

If you're doing a huge batch, maybe value the entire thing a bit more. Like $10.

Hey, when I place my order for 3 sets to Canada, they better be valued at $1.

Bruno