Converting/Converter for using full height adapters in half height bays

Our agency has procurred thousands of newer HP/Compaq computers. Unfortunately, they are smaller SFF cases which only have 1/2 height bays. We have many users that require dual monitors and we use adapter cards for this purpose.

Does anyone know of a conversion kit to convert a full height card to 1/2 height?

Personally, I would like to purchase USB dual monitor adapter which are cheaper than 1/2 height cards.

Any help would be greatly appreciated.