We've done it here for a long time. We have 500,000 to 1 million cgi hits a day. All of them pull the content in from external files that is overridable depending upon which host you are on.

As for the $ signs. Our html guys haven't cared about it. However, I would suggest using something with a beginning and end delimeter such as __variable__, or ^variable^, rather than $variable. Using beginning and end delimeters avoids the problem of swapping $20.00 or putting a variable inside of \w text (try to swap out ABCDEFG$variableHIJK).

Even if it is a small operation, having the code external will save you time in the long run.