Just water plus detergent and vinegar
I guess you haven't heard of this, but you can get rid of fleas without buying expensive shampoos or anti-flea stuffs. Just mix dish washing detergent and vinegar to water and rub it all over your dog. Don't rinse until five minutes. You might also want to get a spray bottle and put the solution in it then spray all over your house where fleas might strive. Remember, only about five percent of fleas are on your dogs and the other 95% reside on different parts of your house. So, getting rid of fleas only on your dog's body will not solve the problem as they will only come back.
Do this everyday until you notice that fleas are already gone. So long fleas!
IMPORTANT: Use light detergent because there are strong detergents that might be harmful to your dog's skin. But most detergents have ingredients that are similar to dog's shampoos so it should be fine.