There are not many places where you can buy organ shoes, although dance shoes are often used instead and shoes of a similar ilk can also be worn. However, organ shoes may be obtained from the following retailers:
Outside the UK
Please note that organ shoes purchased from abroad may appear cheaper than UK retailers, however there is likely to be a Customs Duty charge which will negate the cost benefit.
There are some interesting discussions on whether organ shoes are needed.
Organ Shoes – Do you really need them?