If I were you, I only would let do that in a very good salon. And yes, that would be probably quite expensive. Most regular hairdressers can't make such a drastic chance whitout totally run your hair. So, in my opinion the best thing to do is find a really, really good hairdresser (best is to find someone that is specialized in colouring hair), or otherwise let your roots grow out an get your lighter colour after the growing out proces.
highlighted 3a hair. Fine strands, medium to high density. Probably high porosity. Growing uit bad layering and aiming for waist lenght!

Pre-poo: coconut oil
wash: CJ Daily fix or SheaMoisture Coconut&Hibiscus
RO + LI: different every time
Styler: CJ Pattern Pusha, CJ CIAB

dislikes: glycerin in low dews, scissor happy stylists, magnesium sulfate

(modified) CG since june 25, 2012
Hiarfinity + extra MSM since March 5., 2014

SL - APL - BSBL- BSL - MBL - WL (stretched)