How to include reserved characters in search criteria

 We use a text index on a table called product_text.  We're having a problem searching the index when the search value includes a reserved word.  We tried using escape characters, but they don't seem to work.  For example:

Select * from product_text where contains (text_block,'$75') > 0

returns the same rows as

Select * from product_text where contains (text_block,'\$75') > 0

which, returns the same rows as

Select * from product_text where contains (text_block,'{$75}') > 0

How do we search for a string that includes $, which is a reserved character? 

Any assistance is greatly appreciated.