How to make a music video? How much would it cost to set up a small not too big studio?

My friend and i are in a band. Its usually us to but sometimes theres more people. Sometimes are voices are either to high or to low for the song so we looked up these links:

http://www.ehow.com/how_4452250_make-low-budget-re...

http://www.ehow.com/info_10016956_equipment-need-r...

http://www.ehow.com/info_8260306_devices-can-chang...

Does anyone know a place where i can get all this but how much would it all add up to? We wanted to make an awesome music video that includes a green screen in the background but do you necessarly need a green screen? Or can you paint wall green? Whats the best stores in California, maybe around LA that i can shop for all this? Please answer my question answering all of this and reading somewhat of the links and i promise i'll anser yours! Thanks!