You can get new or second-hand from several of the 'department store' type shops here such as Guitar Center or MARS Music. They are more tuned to selling new stuff heavily discounted, but usually have some used gear.
www.guitarcenter.com
www.marsmusic.com
They are very much like the big shops in England - generally not very knowledgable sales people - and may not ship to UK.
The best way to go is to deal with a long-established guitar dealer here, most of whom are very familiar with shipping instruments abroad. If you're looking for a vintage or really nice instrument, try the following websites:
www.gruhn.com
George Gruhn's store in Nashville, Tennessee is extremely reputable - they will give you a very accurate description of any instrument over the phone, if they say mint condition, it means mint condition, if they say it's a 1954 Les Paul, it's a 1954 Les Paul, they'll send it to you and you have 24-hour approval. If you don't like it, send it back. All you pay is the shipping.
www.mandoweb.com
Mandolin Brothers in Staten Island, New York. Leans more towards acoustics, but all the same things apply to Stan Jay's store as George Gruhn's. Extremely reputable and the same high quality services.
I have dealt with both of them long distance and they were both totally professional and I got exactly what they said I was going to get, and what I paid for.
I have also sent back instruments to both and they didn't even ask why. I said I didn't like it, and they said send it back.
www.williesguitars.com
Willie's American Guitars is in St. Paul, Minnesota. They are much smaller than either Gruhn's or Mandolin Brothers, but the same commitment to quality and service exists there. I always dealt with Nate when I lived there, but I'm sure they're all good.
Email me if you have any more questions, I'm happy to help.
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