If you have the time to remove the flooring and reinstall it you can surely also do the leveler and not have to pay someone.
http://www.bing.com/videos/search?q=floor+leveler+over+wood&qpvt=floor+leveler+over+wood&FORM=VDRE
You could have just used 30 lb roofing felt to fill the low spots.
http://www.bing.com/videos/search?q=floor+leveler+over+wood&qpvt=floor+leveler+over+wood&FORM=VDRE
You could have just used 30 lb roofing felt to fill the low spots.