Here is a simple, token-replacement template engine for PowerShell that you might find useful.

You use it like this.

Merge-Tokens 'Hello, $target$! My name is $self$.' @{
        Target = 'World'
        Self = 'Brice'
    }

The output of that command, as you would expect, is this.

Hello, World! My name is Brice.

Enjoy.