polonium-210 does appear to have plenty of industrial uses but Lazar is a nut.
A few orders from areas with Al Qaida presence as well as other places where the haters hang out, I'd reckon ....
And no legitimate company would buy something like this from anyone with a resume like Lazar's, not to mention from someone who is offering to deliver it via a patently illegal method (USPS flatly prohibits mailing radioactive materials).
Ping
I've purchased from Lazar/United Nuclear before, and it is operated as a perfectly legitimate company. Their high power magnets are some of the best I've seen, and the lump of uranium ore on my bookshelf has always been an interesting conversation starter :)
They sold out of them, but at one point Lazar was even selling unused reactor fuel pellets. Completely useless for building a weapon or a reactor (he'd only sell you one), but it was still suprising to see that high-radiation items like that can be sold legally. There are LOTS of things on his site that will kill you or injure you, a fact which the site warns you about repeatedly.
FWIW, he loves press like this. It drives people to the site and drives up his sales.
Hmmm. Guess one just needs to go with a (barely) visible amount, then, and hope the blue glow isn't noticed on the canape.