Bimmian has a nice one called Solaris Invisbulbs
Link:
BIMMIAN
A cheaper way is to
lightly spray your ambers with high temperature silver spray paint. I did this and am very happy with the result for the price of a spray can. If you don't get it right - too much, too little or just an uneven coating, it will wipe off with mineral turps even after half an hour and you just reapply the spray again until your happy.
I did this back in November and all the bulbs work fine still.