Looking to acquire printer for a school

[vancitysage]

I need to acquire a 3D printer for a university metalsmithing program. Any input on what machines might suit my needs would be greatly appreciated. To start out, the budget is $500, this does not have to include the cost of shipping. We only need one extruder, the primary use would be for casting in bronze and silver, although I'm sure at some point it will be used for stand alone pieces. I have had good results casting PLA, and would like to continue with that medium. Our lab has both a Mac and a PC to choose from to run the software. Additionally, do any of companies that make or sell printers offer academic discounts? Thank you for any insight you might shed