Yes, you need to be an Ebay member to buy from an Ebay seller, but becoming that is easy and free.
The belts pictured looks round to me (item 350020950050) and the listing also describes them as being round. I never bought from this Ebay member myself but looking through his feedback I would have no worries doing so if needed.
If you still have the old belt, you can get an "emergency solution" by cutting out 5-8mm from the old belt and glue the ends back together using superglue (cyanoacrylate). Afterwards grind the joint lightly using fine sandpaper to remove any glue remains on the surface. As said, not the best solution but it may keep you going until a new belt is found.
Martin