buy the 1-10 journeyman illegible scrolls off the broker or run KA solo zones and hope they drop, run heroic KA zones with 2-3 well geared players for chances at 1-10 expert tier illegible scrolls or buy them off the broker, for adept tier you could run expert zones for the pages, for master and gm you can research those up slowly for free. the real roadblock at the moment seems to be the 11-15 spells, not many of those pages have been discoed, but it's early in the expac.
I've seen Master ascension scrolls, illegible pages and sometimes also the recipes, when running Kunark Ascending Expert zones during the Summer Ethereals event, they were sometimes rewarded from completing daily / weekly missions, and I think (don't remember exactly) they could also drop from last name in zones. However Expert heroic zones are quite more difficult than normal heroic zones, so I dunno if you can solo the first, yet.