How can I get my hair from fading brown to light ash brown/dark ash blonde at home?

Hey guys! About 3 months ago I got my very blonde hair dyed back to my natural color which is a light ash brown color. She did it way too dark, and now its fading to a brassy orange-red color. I want to get my hair to a very ashy light brown/dark blonde but I don't want to go to the salon and spend a ton of $$! Does anyone know how I can achieve this color? Do I need to buy a toner from sallys, do I need to pull the brown dye out and re dye my hair? I've been looking at wella toners and hair colors but I dont know if its only for blondes or not? Is anyone familiar with this brand? Right now I'm thinking of mixing a violet ash toner into a light ash brown hair color. Would this work? The brown dye is PRETTY faded at this point so my hair isn't that dark