Vape Wild has sample packs in 10 ml. Six bottles for a very reasonable price.
The Vapor Room, I believe, has sample packs that you can order. At least they used to.
Depending on what you are looking for and what you expect, there are quite a few vendors that do not offer "bundle packs" per se, but who have reasonable enough prices that make it well worth your while to order a few flavors at a time to get a decent feel for whether or not you like their eliquids. My daughter and I like Mt. Baker Vapor, Vapor Bomb, The Vapor Room, ITC Vapes, Seattle Vapors, Vape Wild, and Mech Sauce.