I bought a car w/out airbags & didnt find this out until after I paid the private party in cash. Wat can I do?

I paid $7800 for a 2007 scion that I knew was a salvaged title, but I did not know there were no airbags. It is around $3000 to get these installed. What should I do with this guy, or what can I do to get the additional money or my money back?? help please!