It's a gamble for sure, and when I've gambled with discus I've lost. It sounds like you're doing your homework, but if possible we always like to see what we're getting before we make the purchase. Just remember, cheap fish are not always inexpensive. If they are sick or have parasites you can spend a lot more money in the long run trying to nurse them.
No one can make the decision for you, and I don't want to discourage you from the hobby, but I would recommend reading and studying so you are prepared. Sorry, probably not much help here...
If possible, I would wait and save up until you find exactly what you're looking for.