I'm sure it would depend on the region you are in as well as other things.
I'm in Florida. I paid $140 to have the extensions put in my hair. It took approx. 3 hours early on a Saturday morning. Before I chose to get extensions at this particular salon I had several consultations and researched the different types of extensions available. I went with the hair weaving way. This way my extensions didn't need to be removed daily and put back in. This also promotes hair growth. They braid your hair across in several rows and weave the extensions into each braid. They leave out a row of your own hair on the bottom,sides and top incase you chose to wear your hair up. That way extensions aren't visible.
On top of paying to have the extensions put in I also had to purchase the human hair. I had a choice of either going to a beauty shop to buy a bag of hair which is synthetically created or having the lady at the salon handmake the hair to be used for my extensions. I chose the handmade hair as it allowed for a more natural look. The cost of four rows of handmade human hair was $125. But she gave me a 15% discount for being a first time customer.
So far I've had these extensions for three weeks. During that time I went away on vacation for two weeks. I really love them. At first I didn't but after a few days I fell in love with them. I'm having them removed next week though.
With weaved extensions you can keep them in for three months. Once they are in you can brush them like normal hair, wash them, curl them, color them, etc. Pretty much everything you can do with normal hair you can do with these weaved in extensions.