Saison's brewed/available in Dallas, TX

Oak Highlands Brewery had a one on tap when I was there and it was pretty solid, unfortunately not canned/bottled that I know of
You have Jester king which is pretty much avail everywhere in Texas
Tallgrass will be here probably next month, and they have really solid Saison Songbird
B-52 here in Houston does a lot of Saison's but unfortunately they don't make it up to Dallas yet
Southern Star just came out with Summer Saison, which is pretty solid
Edit:
2 new ones also coming this month
Funkwerks – Amarillo Single Hopped Imperial Saison (B, K)
Great Divide – Nadia Kali Hibiscus Saison (b, K)
I had the Nadia up in Tulsa last weekend and it was nice

 

Depending on where you are in Dallas, On Rotation makes some good house saisons and worth the drive to check out. Particularly their jalapeno saison, which I don't think is on as I write this. Collective Brewing in Ft Worth makes a nice and interesting saison, Urban Funkhouse. I highly recommend checking that brewery out in general. I tend to not like the sweeter saisons, like Martin House's River House. However, if you did enjoy River House then be on the lookout for their Hibiscus Saison (River House + hibiscus) and River Horse (barrel aged River House + brett).

I prefer saisons that are a little tart and very dry. My favorites tend to be:
Oddwood Ales out of Austin
Jolly Pumpkin
Jester King

Enjoy your search!

 

Saison Dupont (in brown bottles) is delicious and easy to get (though I just go for Funkwerks if I don't feel like spending the extra cash). I second sethsicles suggestions as well.

 

Saint Arnold's current specialty seasonal (Icon Gold) is a very good, dry, saison brewed with Texas honey. Very reminiscent of Funkwerks and DuPont, but ~$10/6pk.

Buffalo Bayou's Rotundone (22oz bottles) is brewed with peppercorns. If you like spicy Saisons, that would be right up you're alley. They have a version out with raspberries now and a peach variant on the way. I'm not 100% sure that makes it to DFW, but it's everywhere around Houston. I also see a lot of last year's batch. The pepper has fallen off and turned into tropical fruit.

8th Wonder has a beer called Pharmhouse. Last year's batch was on the sweeter side of the saison spectrum, but very good. It's draft only for now. Again, I'm not sure how much they're in DFW.

I'll second Martin House variants, Oddwood Saison, and Southern Star's new Saison.

 

If you local store carries Southern Star, they make a decent saison. Not brag worthy, very typical check in the box saison that's a great hot weather beer. I also recommend their blond ale, it is their biggest seller. Their Burried Hatchet stout is also good.

 

If Chimera Brewing in Ft Worth ever makes it again, check out Petite Rhub.

When they build a Flix brewhouse in DFW, you have to try Saison de Walt.

Also, Small Brewpub in Oakcliff makes some nice saisons. That place is amazing, dont miss out on them.