Well, Bobby may have some very nice high whites coming this season. (not Chacoan-though he has those as well) While I would say that's your best bet for selection and quality, they do change a LOT as they grow and what started off as a primarily white tegu could turn darker, normal-ish or even whiter. There's no way to be certain of the outcome of your little tegu when it's fully grown, unfortunately.
That said, Varnyard is the best bet for what you're looking for as he breeds for temperament, size and color.(and he's taking deposits now!) There are none available as of yet, so you'd have to wait. UNLESS you get
REALLY lucky and find someone tired of their animal.
Good luck to ya!