Hi Kristian, Welcome to the forums
How short is short? I personally like them short :P one of mine comes up halfway to my calf. (without alterations!)
with regards to your question. you can try
http://www.bujindesign.com/
http://www.alpha-net.ne.jp/users2/iwataco/frame2e.html
http://www.tozandoshop.com/category_s/36.htm
They're usually the mainstream stores that most ppl order from. Personally I've never tried out their pants before.
I got the deluxe cotton gi from
www.ninecircles.com here in the UK and the quality is quite good. I think they do the pants separate.
On ebay, as long as you get one from heavyweight material, trousers for Judo, they should be ok. again as you've mentioned from the description and pics it really is hard to tell. that's the risk usually one take with ebay