Hair Dye Advice

[nixpix]

Any hair dye advice much appreciated!
Ok, here's the background info:
My natural colour is mid brown and I've been dying it forever. Up until 18 months ago I had blonde highlights, then went back to natural colour (using permanent dye), then thought it looked really flat, so went various shades of red- reddy browns. (Using permanent dyes). I got sick of it fading really quickly and ending up redying it every 3-4 weeks. So I thought I'd try to go back to plain brown again,using Nice N Easy, and it was fine at first, but a week on and it's done that horrible thing when it's darker at the ends and lighter at the roots. What should I do? Am loathe to dye it again, as worried will make it worse. Would have it done professionally - but it's so bloody expensive, especially if I want to keep on top of the emerging greys. Can anyone recommend a good hair dye? Should I consider semi-permanent dyes as I end up re-dying so much anyway? My hair is ear length, fine and greasy so washed every day.
Any help much appreciated!
Nix

I'm no expert, but if you don't mind dying your hair every 2-3 weeks to get rid of the greys (like me), what about using a semi permanent just on the roots (in a shade which matches the rest of your hair).

I use Lloreal Casting Creme gloss in Chocolate Brownie which is really nice and leaves your hair in much better condition that permanent colours. I was trying to get away from reddy shades but find that plain brown shades are a bit too flat for my skin tone so will probably stick to this colour for a while.

Just use the nice n easy root touch up kit in between full dyes, cheaper, really quick, and wont over process the rest of your hair. really easy to use too