Cashforclunkers automobile program question?

does the cash for clunkrs program mean you get a total of $3,500 - $4,500 for your car if it qualifies? or does it mean whatever your you get for your car plus a credit of $3,500 - $,4500 The reason Im asking is because according to kelly blue book my 1999 mountaineer qualifies and since i commute to work I was thinking about buying a cheap honda civic, but i don't have much to spend.