You're in the ballpark, 5x profit is typically the absolute max and that's for something established with steady or growing revenue. If you're down 10% YOY for the last 18 months you'll be lucky to get half that.

That being said there are always exceptions - my current business partner bought a side project for 10x gross profit because he had a lot of contacts in the industry that the owner didn't and was still able to make a great return when he sold a few years later.