First, you need to be a little clearer on what you want to study. I assume you are interested in a taught masters degree rather than a research degree like an MPhil. One factor that causes some adjustment for American students is that university education in Britain and Europe is much more specialised than in the USA; this is particuarly true at first degree level but you have to remember that the indigenous students will have had some years of focus on one area already.
Fees for international students have risen sharply in recent years (international in this context being outside the EU) but they are still very competitive compared to North America.
Much depends too on where you received your first degree; some institutions are recognized as providing an equivalent education at Bachelors level while others are not. Allied to this - and assuming all is well on this count - you should consult The Grants Register 2011: The Complete Guide to Postgraduate Funding Worldwide, published by Palgrave MacMillan. This is about the most exhaustive and detailed compendium of grants and awards for all nationalities. Most major Universities offer some form of postgraduate funding, while many from the USA take out loans.
All the best in your search.
I trust this hasn't got too far off track.