I have an HP LaserJet 3015 that was bought on eBay new-in-box for little more than the cost of shipping. It was a discontinued model by about 2 model cycles and has been a little workhorse for the past 6 years. It is an all-in-one that uses toner cartridges. I have always been impressed by the HP printer lines and especially their laser printers. They are durable, reliable and do a quite decent job of what they are supposed to do.
If you decide to go the eBay route, make sure that you google further information out on the internet. There are a number of HP 4500 listed as 'laser' but they are ink jets rather than toner and they are color ink cartridges which you might want for your personal life but there is little need for in mystery shopping.