Not in Europe and many other developed regions. The 4.5V compact Mac PRAM battery is prohibited in its original design for environmental reasons. However, it was used in some high end cameras that are collectable, so you can find an equivalent from some specialists.
In the UK, an equivalent is available from http://www.smallbattery.company.org.uk/ Search for a 523 -- the info pages will confirm that you have found the right one. It is quite expensive, so I would check oher battery specialists too.