Wild Fabrum now carries Essex in the US. Import prices are higher than buying direct from Essex, but low flat rate shipping.
Noble Knight also has them at very good prices, but stock levels are generally low. Worth a look if you're shopping for army packs. Trickier if you're looking to build an army a la carte with multiple different figure packs
I generally buy direct from UK. The baseline prices are lower than import markups (except for Noble Knight), the shipping may or may not work out higher depending on package size. With recent exchange rates, it usually works out about the same as ordering from the US and they always have the full order.
Never hurts to fill the cart on different sites, check the total with shipping and compare exchange rates.