I am visiting a friend in Houston this weekened and I tried googling live fish near houston/discus fish near houston but google does not have very many matches. If I do live fish in austin there are several places that come up with addresses and websites and all that great stuff. You would think Houston would have a lot of sites out there.
The absolute best place to get discus near Houston is Houston Aquarium Warehouse in Stafford, TX, just a little bit off of Hwy 59. Incredible quality for the price. The owner is a distributor to a lot of different stores, so you’ll be able to pick them up cheaper than in other places and he’s got a nice price range starting around $25 or $35 to $150.
He’s also got a lot of rarer aquarium fish suitable for planted aquarium tanks like apistogrammas and rams.
http://www.houstonaquariumwarehouse.com/index.php?option=com_content&view=article&id=54:discus-list&catid=3:in-stock&Itemid=56
Another good place is Xtreme Fish and Pets off of Bellaire. He often sells large discus for around $50 or $60. The owner is a great guy, and you can often find a couple oddballs around the store too. If you buy enough, you may be able to negotiate a lower price with him.
http://www.xtremefishpets.com/storelocation.html
Everywhere else, the discus are either pretty poor quality or way overpriced.
There are a couple of other good fish stores in Houston for different reasons, feel free to email me if you’d like to know more, but these are best two places to get discus in my opinion.