This was best price I could find by a considerable margin, so I'm very pleased (still bloody expensive, though!)
For those having trouble removing and attaching the strap, there are currently two excellent videos on YouTube showing exactly how to perform each operation. For me personally, watching these videos before attempting to replace the strap made things pretty much straightforward and simple.
How to remove a Suunto Core strap: [...]
How to attach a Suunto Core strap: [...]
The videos look to have been made by Suunto themselves, so maybe they can also be found on an official Suunto website somewhere (but I'll leave finding that one out to someone else)