Custom variables in node content Is it possible to use custom variables in content?

For example we have the price of a product which is listed on a large number of nodes as £9.99... This price then changes to £11.99. Updating this price becomes a pain!

What we would like is to be able to have a variable such as [product1price = £9.99] which we can include in node body. Then should we need to change this price, we can edit the variable to instantly update it everywhere it appears in the system.

Does a Module already exist for functionality like this?
You could implement custom tokens, and the coupled with the module http://drupal.org/project/token_filter - your content will be rendered as per usual.

In this way you could have a token:

[price-tier-1] = $9.99

and when the price changes you only have to change the token value (in one place, in code)