About 4 months ago, I died my hair red. I loved it, it looks beautiful with my skin tone, and it really brings out my green eyes. Since then I died it in that color 3 more times. But I'm a student, and so is my husband. I didn't really realize how expensive it can be to color your hair every month.
Now I just want my natural brown color back, and I want to do it without damaging my hair, or paying a lot of money.
Any suggestions?

You've colored your hair 4 times in 4 months? I, too, color my hair red and only retouch every 12 weeks (3 months).

You could color you hair back to the color it was previously, just as you did the red. You will just have to find the color that most resembles your natural shade. I would do it after most of the red tones have faded.

Twice of those 4 colorings were just doing roots. My hair grows really fast, half an inch in 3 weeks, so it was kind of necessary.

If I just die it brown, won't the red show through? That's what I'm worried about the most...
I want the brown to come out beautiful and really permanently cover the red.

It might be worth it to go to a stylist for the first transition back. She/he would be able to forsee any problems with the red showing through.