Hi Spidermanuj - wow 50% NPB rate would have me tearing my hair out! I took a look at your auctions, and also specifically your winning bidders. It looks like a high proportion of your winning bidders have zero feedback, or are very new to ebay.
One thing i find with new bidders is that they just don't read the complete listing, they just go ahead and bid. It's quite likely that when they find out that they face a $35 US shipping charge that they hadn't read, they back out of the deal.
Knowing that many of your buyers are new or first-timers, it might be a good idea to change your listings (which are very nice and well done) to focus on the shipping charges and final details more clearly or prominently, so that the bidders are fully aware of them. You may loose some bidders who are scared away by the shipping costs, but it would only be the NPB who you would lose, the ones who back out after becoming aware of all the terms & costs.
A UK buyer might not be so thrilled in the end to learn that they will face customs charges on an item coming from Canada or India, when at first glance they thought the item was located in the UK - it might help to put Canada as your item location up top in all of the listings to avoid any confusion (although i know my listings say Ontario, then USA...some glitch due to being registered on the US site, so there may be no way around it)
I hope your numbers improve, hang in there!