As far as I know, Congress has not passed any laws prohibiting the use of flashbulbs. I have two or three thousand squirreled away. A few years ago, on eBay there was a guy selling cases of Press 40 bulbs and I got seven cases of 120 bulbs for fairly cheap. There are still lots of M-2 and M-3 bulbs available. Press 25's and #5's are common but run about $1 per bulb. If you want something specialized, like the bigger focal plane bulbs or infrared bulbs, they can be quite expensive.