Here is the start list. I have added pros and cons section under each seller in order to give a better description of each seller. I have tried to be as objective as possible. As new experience comes, this list can be collectively updated.
Jadefinejewelry aka jojojade (2 sites)
Pros; Huge selection of grade A jades, a jade processing factory which can help you find and even make a specific piece.
Cons; It is a large company and operates like one, can take days to get back about inquiries, can be overpriced without negotiation.
GeGe Designs Etsy
Pros; Wonderful seller, small selection of older, unworn jades which are grade A. Interesting things, layaway and negotiation.
Cons; Small selection.
Alohamemorabilia Etsy
Pros; Sells vintage jades, (mostly grade A, be sure to ask), great value for the money, old mine material, layaway, negotiation.
Cons; None
Ultimate Jadeite Etsy and Ebay
Pros; Very kind seller, bangles with great qualities such as translucence for affordable prices sometimes because of minor other flaws, detailed descriptions and pictures.
Cons; No negotiation.
3jades Ebay
Pros; Great selection of nephrite jade bangles and beads especially. Best offer option, reasonable prices, interesting selection.
Cons; None.
Jade Nature shop Ebay
Pros; Wonderful selection of mostly jadeite jades, especially pendants, reasonable prices, best offer option, good pictures.
Cons; None.
Enijew Ebay
Pros; large selection of very affordable jades such as bangles and pendants, good service.
Cons; Pictures are not the best. Reported that items look better in person.
Suzanne's_Corner Ebay
Pros; Large and interesting selection of A, B, and B/C jades, kind seller who is quick to fix mistakes, best offer option, sometimes accepts low offers on pieces.
Cons; Very blurry pictures, Sometimes sends the wrong items, flaws are not clearly described or pictured, hard to see description of treatment. (look for 100% untreated jade instead of just jade under description.)
Unijade Ebay
Pros; very affordable jade items, easy to contact, nice seller.Best offer option.
Cons; Some items do not accurately show the flaws in pieces.
Gojade Ebay
Pros; Large selection of very affordable jade pieces. Descent seller, best offer option.
Cons; None.
Preciousjadeite Etsy
Pros; Medium selection of mostly jadeite pendants, very affordable, good pictures.
Cons; None.
Desire Treasure both on Ebay and homesite
Pros; Lovely selection of mostly light colored bangles, some pendants, some Nephrite jade, high quality, good pictures, detailed descriptions, negotiation, layaway, flexibility.
Cons; Tends to mostly have bangles of a certain color range.
Eragem
Pros; Fine selection of vintage jewelry with some jade from time to time. Negotiation and layaway.
Cons; Some items seem expensive.
Allan from Jadedivers
Pros; Wonderful person, a gem to deal with, fabulous artisan, hand made bangles, earrings and pendants, very rare and hard to find nephrite jades, some flexibility and negotiation, layaway, one of a kind custom work.
Cons; None
GemtownUSA Ebay
Pros; Great selection of jewelry and gems, mostly STONE bangles such as chalcedony, rose quartz and aquamarine. Very reasonable prices.
Cons; None.
Reikocrystalbeads
Pros; Large and unusual selection of mostly STONE jewelry such as bangles in interesting, harder to find stones. Reasonable prices.
Cons; None
The Jade Mine
Pros; Carries selection of Canadian Polar Nephrite Jade. Interesting designs with some items, range of prices.
Cons; None
Jadepeony Etsy
Pros; Selection of Nephrite Jades, mostly Polar. Range of prices, interesting designs.
Cons; None.
Piccolinagems Ebay
Pros; Wonderful, kind seller, small selection of high quality merchandise, good photos, make an offer option.
Cons; None.
Mason Kay
Pros; Lovely, high quality jades, custom work, jade testing, trunk shows throughout the U.S.
Cons; Must either contact them for prices and items, or find a retail seller, established name which may be a part of the price.
Deborah Wilson
Pros; Jade sculptor, selection of fine, artisan hand made jade bangles, pendants and earrings, jade workshops.
Cons; None.
Jade Los angeles Ebay
Pros; Nice selection of mostly jadeite but some nephrite. Kind seller, best offer option, negotiation, good pictures.
Cons; None.
What about seller shishi.09 (also Ebay)? These four have caught my eye very much (quite low prices and great variation of pieces, from all-around carved or twisted to rough and "unfinished", which I actually like though it may go against aesthetical canon - guess I´m in the minority there) - what do you think, do any of these seem actually "100% natural jadeite", as purported?:
