I've never used RK or TFSource before, the pricing has always come across as a bit much. I've used BBTS a few times and no problems with them. Packaging is always first rate and arrival times are what I've expected. I do agree with everyone here that eBay has gone down hill big time! So many jacked up prices on supposed "original MIB" or "guaranteed not a KO" and on shipping. Most of the time I try to buy multiple items from a seller just to keep costs down. Though I have to give a thumbs up to transformerland . I have bought of the guy's website for years and never had a problem. Shipping is fairly priced, always willing to negotiate, well stocked (though the popular stuff goes fast) and great communication. CapturedPrey also gets a nod from me. I've added numerous stocked items to a pre order I have with no problems.
WANTED BOTS: G1: Horri-bull, Snarler, Mainframe, Chop Shop, Ransack CHUG: Spin Out, Cordon, Brotropolis Rescue MASTERPIECE: Acid Storm
ENERGON: Six Shot