You need to figure in the following costs, is it worth it.
A semi complete engine to a complete engine and gen head = renting a trailer, 35 UK pounds a day, and mileage, fuel is expensive here, and a small allowance for wear and tear, so you're looking at about 100 pounds or 150 bucks to go and collect your lister and bring it "here"
if it is parts, such as flywheels etc and can be securely put on a pallette by the vendor costs are lower, maybe 50 pounds per pallette to get it "here" by commercial tucking
OK, so now it is "here"
it needs packing for shipping, doing it properly means a steel base fork lift ready, and an angle iron frame with plywood panels, this is going to cost 200 pounds or 300 bucks in materials, it is still sat "here"
if it is a smaller item such as parts of flywheels and can be rigidly attached to a strong wooden pallette and then saran wrapped then this is less, maybe 50 pounds or 75 bucks
to get it from "here" to "there" you need a shipper, you can arrange that you end or you can ask me to give you a couple of websites for local companies here, they can do all the paperwork and advise on collection from "here" and of course what shipping and import duty is
those of you with USAF connections will be best getting it sent from "here" to a US airbase.... lots of angles here if you play it right....
"here" is Exeter in the south west of the UK, we have a local airport if you are going air freight, nearest shipping ports will be southampton, bristol, or liverpool, if going by sea, got to get there by truck though
UK > USA sea freight works out about 200 pounds or 300 bucks for the first 4 cubic feet, and about 60 pounds or 90 bucks for every 4 cubic feet after that, this is known as "groupage" and works out far more expensive than by the 20 foot container, which could be as low as 1000 pounds or 1500 bucks.........
bottom line here is it is not a cheap option, you won't beat listeroid prices, but if you insist on a genuine item and are prepared to pay the premium it can work out OK, economic viability only comes about if a group of you get together with an ebay shopping list and ship when the list is complete in one 20 foot container
cheers