Escape sequence for $ (dollar sign) in T-sql script
Are you executing the script with sqlcmd? It will interpret $(variablename) and try to expand it.
You can disable this using the -x command-line option.
Oh, if you're using Invoke-Sqlcmd you can use the -DisableVariables parameter.
I was assuming you didn't want to have the sqlcmd variable substitution done. If you were just trying to get the $ past Powershell, use the back-tick (`$) as in another suggestion.