The computer printer (a RICOH model) in our office does this as a setup option - for example it offers portrait, landscape, and double-sided, but the two you'd be interested in are 'paper saving' which is every four A4 document pages printed half-size onto both sides of an A4 sheet, and 'booklet' which is the same idea but all the pages re-ordered so that the output is ready for folding and stapling. All you need is an e-mail friend who works in an office with one of these. But if you can't find one, that's how a copy shop would do it for you; no program, all done in the printer itself.