Here in Italy is pretty easy to find (literally. S.cingulata, for instance, lives in the wild, here) and buy those, via Fa(r)cebook or directly from breeders, and at IMO very interesting prices, especially for S.hardwickei.
No shipping outside the boot, of course.
Depends where you live... The fact you're asking in English means you're probably in Australia, Canada, Great Britain, Ireland, USA or one of the many other English speaking countries in the world. Am I right? ;-)
But the less pedantic answer is yes, you can generally trust online dealers. Most of them have accounts on here with review pages, so you can find out about them first. Do a search in the classifieds for "scolopendra" and you'll get a fair idea of people who regularly stock pedes.