Selling jpeg file?

I recently had a request by someone who wanted to purchase an image of mine. I made the image available for print only for them to say that they were only interested in the high res jpeg file so they could print it on glass themselves. I've never licensed an image before and I kind of feel this is what is leaning towards. A few things made me ask questions however. First and foremost, the "client" is not from this country (I don't believe) and am curious how I could receive payment from overseas and also how much to charge?. I do have a pay-pal account, but trying to figure how one would get the funds into that account. The other thing, is should I include my digital signature on the file itself? For me the image seems like it could easily be cropped off and passed off as someone else. I'm not sure what size they are planning to print on yet and would appreciate any help and suggestions how to deal with this. I'm just starting to make sales on a consistent basis, but never had a request for just a file. So I am a little skeptical about this as of now not knowing how to handle this.

I use Paypal quite a bit for business. It is very easy for someone to send you money from overseas. If they are telling you it is a problem then I would be suspicious. Bottom line is.... get your money first and make sure that it has cleared your account before you send the file. Once you have your money the rest is easy.