I've seen quite a few of these on ebay.com (and similar on ebay.co.uk). In general, if you buy a horn on the Internet you don't get the chance to try it first. Even if you try a similar one you may have reason to doubt whether the build quality etc is consistent.
I believe (but have not confirmed) that the Selman horns are built in China/Taiwan and I suspect are similar to the Venus horns (possibly identical). Some of the Taiwanese instruments eg Stagg, Virtuoso etc have established a reputation for consistent quality, excellent value (against traditional and well known brands) - albeit student instruments.
If your brother needs an intermediate horn (ie he has progressed beyond his first F/Bb double horn) then the least expensive option is to buy a second hand lesser known brand horn eg Hans Hoyer. However, these really need to be tried by your brother to make sure that they suit him and his likely style and genre of playing (wind band, orchestra etc).
http://www.hornplayer.net usually have quite a range of horns listed.
In other words, as a first (student) double a Selman will probably be OK (you can also contact people who have purchased them on ebay for their experiences). Be prepared for it to lose value faster than a well known brand!
