just so you know, robots find the "mr. roboto" stereotype highly offensive. most of them actually prefer hearing julie andrews singing "the sound of music". they also like classic hip hop especially KRS-1.
just did some googling and you're right you can still get them. you can even get g through J class, though most of these require certification of some sort to order. there was a time when all these e's and f's were unavailable and several of my favorite suppliers shut down because of the change in regulation. evidently things changed again when i wasn't looking. (i havn't done any rocketry since the 70's so we're talking about a 40 year blindspot on my part) i mistakenly assumed that in the post 9/11 america these would all be banned, i was wrong. :) ps- when i was a kid the local hobby shop carried up to D's and an hour's drive or 2 would get you to a shop that carried the E's and F's.