Really, if you can only get one, you should at least save up until you can get 2. More would be much better.
Kas, discus don't need daily water changes in general. It depends on your set up and what your doing. In BB tanks and grow out tanks yes, because you're promoting rapid growth. Also, many discus tanks are overstocked or at max stocking and therefore do need dailies... however, there are a many discus tanks that only get 1X a week 25-50% changes. This is much better to do with adults because their already grown out. I also use the "plop and drop" method when getting new fish, and I don't exhempt the discus from this. Discus are actually very forgiving fish... all and all, I think their easier than pet-shop guppies. You just have to understand their basic requirements like all fish.