$3,127,795,167

A new report from the Economic Research Service of the USDA estimates that that is how much illnesses and premature deaths from E. coli and Salmonella cost just the US every year. I know that it's a fuzzy number because of all the assumptions and guesses that go into it, but it's the best number we have to work with.
Also consider that there are a lot more bugs out there that make people sick. The CDC estimates that there are about 76 million illnesses, 323,914 hospitalizations, and 5,194 deaths (again, just in the US) every year caused by foodborne illnesses. Basically, you have a one in 4 chance of catching a foodborne illness every year.
A report earlier this year estimated that the total cost from these illnesses was something like $152,000,000,000 (yep, Billion).

What should this mean to you? Well, besides hoping that you won't be one of those getting sick, I'll talk a little about what you should do to avoid some of these bugs.

First thing, get a thermometer. You can get a decent one for about 10 bucks. You should get one you can calibrate so you know the actual temp and can check it occasionally. If you're cooking meats make sure you get it to the right temp. Chicken is 165 F. Ground meat is 160. Steak is 145.
Next, use different cutting boards and knives for meat and ready-to-eat foods. Cross-contamination is easy to avoid, if you're careful.

I know that it seems like there's a ton of information, but once you learn the basics, it's pretty easy to minimize your risks.