Yes, incorrect punctuation can actually cost a lot of money. A very interesting story about the expensive consequences of a misplaced comma has been widely reported in the mainstream news.
The background of the story is that two companies in Canada entered into a contract and one of the companies wanted to get out of it by relying upon the following clause:
“This agreement shall be effective from the date it is made and shall continue in force for a period of five (5) years from the date it is made, and thereafter for successive five (5) year terms, unless and until terminated by one year prior notice in writing by either party."
Company A wanted to get out of the agreement after five years, and Company B said, "no way--the contract requires that you stay in the agreement for another five years!" After going to court, the judge ruled that the existence of the second comma (right before "unless") means that Company A can, in fact, get out of the agreement early and so Company B ended up losing about $1 million dollars in continued business. If that second comma wasn’t in there, Company A would have been required to continue with the contract and pay Company B another million bucks.
The moral of the story: misplaced commas can cost you!