Are there any opticians that can make lenses thinner and fit them into the frames without costing a fortune?

Yes: Glasses lenses can be made thinner by using what is called a high index material. These vary in price from pretty expensive to only a little bit more than standard plastic. Some new lenses called "free form" lenses are significantly thinner particularly at the edges but are quite a bit more money.

Sort of...: They use blanks that can be thinner, with high index lenses, but they can cost a fortune depending on how much more thinner lens you want compared to a standard blank.

Check around: Many US opticals are owned by an Italian firm, Luxoticca, that has driven up the prices in their outlets (such as Pearle, Sears, lenscrafters, etc.). Costco is less expensive as they are not owned by Luxoticca and you can get some bargains from smaller independent optical shops. Consider also purchasing eyeglasses on line which is now become more and more readily available.