Gosh, ya think so? I find it soooo easy to buy on ebay. . . . Haha, too easy! 
For whatever reason the Canadian ebay does not yet have the shopping cart feature. The UK and US sites have it, but if you shop on those sites it is imperative that you ascertain in advance whether the seller ships to Canada. Many sellers on those sites do not.
That said, if you are on the Canadian ebay site and you buy multiple items in one currency (usually US dollars) when you click Pay Now you can pay for the lot all at once at the checkout. If you've got items in both pounds and dollars, you'll simply have to 'make two trips' so-to-speak.
If you wish to purchase multiple items from one seller, read through the listing(s) to see if the seller offers a discounted combined shipping rate. Most do, but there are some sellers whose shipping fee is so low (or included) that they are unable to do so.
When looking at a listing, if you click on the Shipping and payments tab it will tell you if a discount is provided automatically at the checkout. Other times the seller must package up the total order and weigh it to be able to tell you the postage cost, so you will need to tell the seller in advance what you wish to buy.
To contact the seller, when you click on the seller's ID name, down on the left you'll see a Contact member link you can use.
Another way is when you are looking at a listing, waaay down at the bottom under the Questions and answers about this item bar you will see the phrase Ask a question. You can click it and choose the Combined shipping query.
See how easy that is? . . . Happy shopping!
