The easiest way to get my natural hair colour back?

Well, here's the story. I have natural medium/light blonde hair and the first time I dyed it I dyed it a dark auburn red. Then, I started dying it a dark brown for a year or so, and just recently I went back to dark auburn red. But the thing is, I'm really sick of dying my hair all of the time and I would just like to go back to my blonde hair.

I know the best option for me would be to go to the salon but I don't have the luxury of spending that much money on my hair. So basically my question is, how can I go back to blonde without spending a heck of a lot of money? I was thinking that I should try going dark blonde first. So, should I bleach, use a highlight or what? Any recommendations on what I could use?

Going to the salon to get it done is just out of the question!

Help please!