[There will be no SE port of this mod. Read here for more information]

The spells added by Dawnguard and Dragonborn will now be sold by vanilla spell book vendors, assuming you have the necessary skill level in the relevant school of magic.

Bound Dagger sold by Phinis Gestor or any court wizard. Phinis also sells Conjure Ash Spawn.
Frenzy Rune sold by Drevis Neloren.
Poison Rune, Necromantic Healing, Heal Undead, Stendarr's Aura, Vampire's Bane and Sun Fire sold by Colette Marence.
Whirlwind Cloak sold by Faralda.
Ash Shell and Ash Rune sold by Tolfdir and possibly Wylandriah (Riften's court mage).
Conjure Mistman, Conjure Boneman and Conjure Wrathman sold by Ronthil at Castle Volkihar.

Conjure Ash Guardian and Summon Arvak are not added to any merchants, since they are both quest rewards and it wouldn't make any sense.

Leveled lists are edited, so there may be conflicts with other mods. Use Wrye Bash to make a bashed patch.