There's a guy like me in every state and federal prison in America, I guess - I'm the guy who can get it for you. Tailor-made cigarettes, a bag of reefer, if you're partial to that, a bottle of brandy to celebrate your son or daughter's high school graduation, or almost anything else ... within reason, that is.
What do the last words "that is" mean?The phrase "within reason" is understood to mean that there are reasonable limits on what has come before - he cannot smuggle a car into prison for you, because it is not reasonable.
Adding "that is" puts an emphasis on modifying what has come before it. It is used to change the intent of what came before it, or to add clarification, especially after a long pause or where there is room for misinterpretation.