If the buyer is a private individual he is likely to incur the following charges:

Sales Tax - 17.5%
Customs duty on plastics - 14%
Excise handling fee - £10 ($18)

The fees are payable on the combined value of the goods and the shipping.

Whether or not these taxes are collected depends how you complete the customs paperwork and what you declare. Even then customs may not assess it correctly if at all.