I've bought from section8superbike via ebay and the stuff arrived within 14 days. I get a lot of stuff from the US (not all bike) and 2 weeks is about typical.
If you use paypal to pay, just follow their resolution procedure (it's on the menu at the top Resolution Centre).
https://www.paypal.com/uk/cgi-bin/we...complaint-view As far as PayPal are concerned, if the sender cannot show tracking / delivery details, so then they cannot prove it was delivered (or a delivery attempt was made) so you get refunded. They claim it will take 30 days, but I've found in the past it takes about 7. Essentially, they take the money back on your behalf, sort it out, and refund you if needed.
Section8superbike's T's&C's have an overseas shipping clause, but don't worry as paypal don't accept these clauses, as far as they're concerned the seller is responsible to track and insure. So file a claim, wait a month and you get your cash back.
It could be they're held up at customs, but 2 weeks is my limit before chasing.