Hi @kiwatradcorp123
If you have purchased the helmet with a Buy It Now, or won an auction, the final price you pay is what is shown in your Purchase History.
The seller cannot make any extra charges afterwards and if they are asking for more postage, then it is also a way of them getting out of paying eBay fees on the postage.
If you have any problems with the helmet once it arrives and you have paid postage separately, you will not be able to recover this payment under eBay's buyer protection policy and will lose out.
The seller could refund your original payment and send a revised invoice thorugh eBay to include the postage if you really feel it is acceptable.
If not, tell the seller they must send the helmet that you have paid for and if they do not, then open an Item Not Received case when the system allows you to and do not be put off by any unhelpful comments or pleas for more money.
Here's the information on your buyer protection
http://pages.ebay.co.uk/ebay-money-back-guarantee/how-to-help.html
