yes, new units are very pricey as people do normal swaps for them, i did find the old style lights modded in the same way though, just dont look as good.
as far as leaking i suppose it is up to the person how well they seal them.
there are a few issues...
condensation, can be sorted with some silica gel stuff put in the back
sealing against weather
DUST - the biggest problem by far and difficult to avoid without a cleanroom environment!