Scuba toys has Dive rite, OMS, and Zeagle stuff along with an assortment of wings and accessories.
Grapevine scuba has some Halcyon BP stuff
Lone star scuba has some deep outdoors stuff that I am not familiar with but I think they have some BP systems
If your looking at technical diving avoid any type of gimmicks when it comes to the setup such as quick adjustment straps and such, think as simple as possible, for standard OW the simple as possible also works and will save you money.
Scuba toys has in stock several types and brands of plates to try out, and an assortment of wings in the store with several options, such as a zeagle setup that does not require a STA with a wing that bolts directly to the plate or a slick setup with a standard harness STA and a very streamlined oxycheq wing, however you want it setup, I HIGHLY suggest however that you get with someone who dives back plate and wing to show you the ropes before you go to a dive shop, not knocking the dive shops, its just that a lotshops that sell them, don't dive them, and when it comes to back plate rigs there are several ways to skin a cat.
I do not work for any dive shops, these are just my opinions