Welcome to the used Cisco market. Consider yourself lucky they'll offer you a service contract on old equipment. It used to be impossible to get one unless you bought new equipment and kept proof of ownership if you let it lapse. It's likely the equipment specific IOS is available from them, but then you pay :o; my ASA-5505 started out at $100 and is $75/year. But then I use it for work...
Or, you could buy a second working one off e-bay and follow these instructions http://articles.techrepublic.com.com/5100-10878_11-5623025.html