I buy all my 'good' lilies from the growers, as you have mentioned above. But I also buy from the Netherlands bulb growers, for sales, just to cut, and some because I just like them. If you're concerned about being able to grow orientals, might I suggest grabbing a few from one of the co-ops. Then if they don't do well, or don't last, you're not out much. Not much going on now, but in spring we will have some good lily co-ops.
I've never had a problem with any co-ops done by Woodthrush or Mamajack.
Here's where you can find them.
http://garden.org/forums/view/...
Now believe me, I am not recommending the co-ops or the Netherland growers as a first choice. Our growers have the best lilies there are. But if you wanted something cheap to try.....then buy the best after the cheap ones do well.