I suppose you require a expansion appliance but first you should go for a manual check up...The doctor/orthodontist will first take your OPG to see the position of roots and then asess how much pressure needs to be requried for their movement. Regarding hte cost, it depends upon the city and dentist, wether s/he is general or specialized...for more info on braces cost you can visit the link...http://www.identalhub.com/article_average-cost-of-braces-for-teeth-431.aspx