Toner cartridges should last you at least 5,000 pages, and at about $60/each, that's $.012 per page. Also assume that a ream of paper (500 pages) is $5, so that's $.01 per page. So, with a laser printer, you're spending 2.1 cents per page, which is damn cheap.
Compare to an inkjet printer, where the ink tanks cost $30 and last 500 pages; assuming you're only printing in black and white, with paper cost that's 7 cents per page.