
Hi Terri
As well as the size and weight of your dog there are other factors involved. Off the top of my head is (a) where you'll be flying from in the US to your receiving airport in the UK; (b) what time of year you'll be travelling - in certain months special AC packs have to be installed to regulate temperature control, which adds to costs; (c) not all airlines will deal directly with a member of the public re animal transport - you may have to source a dedicated animal carrier service to deal with receiving, crating, customs paperwork etc.
Prices can vary enormously - when I sent a pup on a direct flight from Glasgow to Newark around 4 years ago we were quoted with prices ranges as much as £600 apart so it pays to shop around and also to ensure you have as much info re regulations from both authorities and from any airlines you're able to choose from.
HTH with some of your queries,
Best wishes,
Teri :)