just because someone may be only 16 does not mean that they do not have an income or perhaps an inheritance stashed away - the problem with this site is that there are too many who are too quick to judge and lecture others rather then answer the question asked - if you don't want to answer the question you would be better saying nothing.....
I would always advise using a lawyer based in the country where you are buying, because they should have more detailed & uptodate knowledge of the local law. However, you might find some large UK firms who have USA offices.
If you are only 16, you would need to check that you could legally enter into a contract - in UK minors (people under 18) may have difficulty in entering into some types of contract.