I think I saw an advert in an old copy of my IMEchE magazine for a firm specialising in stainless fasteners, especially unusual ones. Problem is the magazine has now been recycled! I'll be looking out for said advert from now on, though. The mag comes fortnightly so they might run the advert again eventually. And the company might even sell small quantities to joe public if we're lucky.
Personally, I can't see the problem with having a mixture of heads. All of the required drivers come in a stubby 1/4" hex size so all you want is the ones that apply to your bike and a holder. Probably lighter than carrying individual allen keys and on a par with a largish multi-tool. I think it unlikely I'd want to undo most of my accessories on the road anyway, so if they're torx I'd just wait till I got home. As long as I could play with (tighten, mostly, if they came loose) the seatpin, handlebars, chainring and also adjust the brakes I'd be happy. Thinking about it, the aforesaid list covers the stuff most likely to be left as hex anyway. So I'd take the allen keys and leave the torx thingy at home.