Welcome to the double rifle investment game!, ......one is never enuff!
First off, decide what your max investment can be, then buy a few good books on doubles so you can understand the lingo and the cartridges available, and the various grades of manufacture, ....high end British, mid-range British, German and Austrian, Belgian, and so on.
Become a regular visitor to
http://forums.nitroexpress.com/ and
http://www.accuratereloading.com/ . Now, follow up the rifles for sale that are mentioned and look them over well so that you become familiar with the styles and terms.
Check out the Martini/Hagn website at
http://martiniandhagngunmakers.com/index.htm for any doubles for sale, and don't be shy to call Ralf and see what he may have or hear about. He knows most of us that are in the doubles field and will let you know who's got anything for sale.
Go to the Calgary show at Easter and look at what's available (there were 11 this year) and talk with those who have doubles on the tables, ask who else is known to be in the doubles game (it's a small world!)
Take your time, listen well, and be ready to jump when something good comes up that is highly recommended by others. But don't get caught like many buying name only, .............there are H&H's that are only worth $3000, and there are H&H's worth 40 times that!
Bottom line is learn before jumping in, .....it's too costly.
~Arctic~