Yoox, good purchases when they have mega sales. If you are after Ballantyne wool sweater can save about £50 on plain sweaters, £100 on pattern; while up to £100 on cashmere. Although limited savings on cashmere.
Wait until the xmas sales, could get cashmere for half-price.
Harrods online can delivery to the US although limited range of Ballantyne, especially during the sales. However, I did pick up two plain Ballantyne single-ply cashmere sweaters for £100 each (about 1/3 of the price) in the first few days of January this year.
Yoox does offer good bargains in the mega clearance sales as Tory Boy says but they inflate their original prices to make their "normal" sales/promotions like the current one seem better than they actually are. In fact many of their jumpers are currently priced higher than the Ballantyne retails and they can't tell you which jumpers are made in Itlay and which are made in Scotland where most of the high-end Ballantyne is still made. There is another US online option www.Bluefly.com which has much better prices but your best bet overall is Berk Cashmere. They really know their stuff, everything they sell is from the Scottish-made Ballantyne range and the prices are cheaper than the actual Ballantyne store in Bond Street charges.