You may want to check out a foremost supplier for touch screens - Keytec http://www.magictouch.com/index.html . They sell, worldwide, a huge variety of this type product. I have on order, for instance, a widescreen add-on for a 17" wide screen laptop - $250 USD. These people have been leaders in this industry for a long time and are very reputable. I have several of their products and can only speak well of them.
Rgds,
Ed