There are more Thin Client computers coming out, but they still tend to be a niche product and so more expensive than regular PCs. One way around this would be to adapt laptop/notebook computers as thin clients. These could be second hand units or cut down ones specially made by the manufacturer, leaving out the components not needed for a desktop thin client.
I toyed with the idea of a "Portable learning centre" made up of a airline carry on bag with a couple of dozen ASUS Eee PCs in it. These would essentially be portable thin clients. The Eee PC is a disk less Lunux subnotebook computer for about $US199 to $US400.
The Eee PC has sockets for USB and an external monitor. So if you plugged in a keyboard, mouse and LCD screen it could also be used as a desktop thin client. The screen, keyboard and battery of the Eee PC are not really needed for a desktop thin client. But they could prove useful for a smart VoIP phone. Having the battery would be useful for a phone as it would provide continued operation during a power failure.
ASUS, and other laptop makers, could make models omitting the LCD screen, keyboard and battery, and stick a label over the latch to make it a desktop thin client. This would save the cost of having to design and manufacture a specialised thin client device. They simply have to tell the people to not install some of the components for a production run. This shoudl reduce the cost of the ASUS unit, for example, to well under $US199.