How much do hair extentions cost?

How much does hair extentions cost? 'Cause I've been thinking about buying some but I just don't know how much it cost.

I either want to dye my hair really blonde or dark dark brown but im not sure it will look good. But I was wondering how much...

do they sell one piece hair extentions at sallys? and how much are they for one?

if I buy 10 inch hair extentions from sallys, how much would they charge to get them gluded or swen in?

I recently dyed my hair black but I hate it .. I want my hair striped then put a lighter brown then lots of blonde highlights...

okay, I wanna get my hair done. I want like 3 or 4 more layers and I really need to get it trimmed. How much money will that ...

Need to get my hair done, dont have a lot of money..just wondering how much it would cost me

how do I sew clips onto hair extentions? I do not know what I'm doing at all

I live in Wales in Uk, we're 30 minutes away from cardiff. Well I was thinking of making myself look different as I never did...

How much do extentions costt?? I don't wanna get them too long just under my hair now for layerss?