Quite a lot of US schools charge $250 for writing out the I-20.
Comparing hours for hours, training in the USA will always be far cheaper than doing it in the UK. The reasons have been posted here many times; e.g.
- it is a full time head-down project, no interruptions due work or family etc
- flying every day (in So. Cal. anyway) which builds competence rapidly
- the flying is cheaper than anywhere in Europe and IMHO always will be, by a big margin
- previous ICAO training is accepted fully, whereas Europe does not (in general) accept any non-JAA training
- much fewer ripoff practices take place
I did my IR in Arizona (aerobatics.com) but sadly you can't do any JAA stuff there.