Today only: como utilizar

"These prices are for today only".

When I hear this I think of something written on a sign at an establishment, and occasions like this require more of a formal type of language. This order has a more formal ring and connotation to it than having "only" come first. It's the same as "authorized personnel only" which we see a lot in movies. So it's mostly a matter of formality that's required for the specific occasion and context in which it's said. Still I think there are cases where you'll always see the word "only" be placed at the end of the sentence regardless of whether or not you want or need to be formal, like "cash only", meaning they only take cash and no other forms of payment, in such cases the context could either be distorted and misunderstood if you invert the word order or it will just sound strange and unnatural. Whereas "these prices are only for today" could still be understood but they place "only" at the end for formality's sake because it just sounds more formal, most likely.