I'm looking for a versatile spinning reel and rod combo that I can use at the texas coast for Reds, trout, flounder, etc. I want to spend under $150 for the rod and reel. I'll be fishing artificials as well as free lining bait or using a popping cork. Any recommendations on specific models or rod and reel? Also, what size reel would you recommend? Thanks!

Size 3000 or equivalent reel, you may get by with a 2500 too. A light 4000 won't tire you out either, but is likely not needed. Fishing the surf you may hook up ojn sometyhing bigger, but a well setup 3000 and rod can bring in a bigger fish.
a 6'6MH o 7MH rod would work well for those species.
There are plenty of rods and reels that will fit that budget.
I have a Shimano Voltaeus and Daiwa SS1300 (used a Shimano Carbomatic 3000 before) spooled with 15lb Daiwa J-braid. I've pulled 28" reds with that setup, and can probably take bigger fish. Flounder and trout are much easier

Bullet proof setup:
UglyStik GX2 6'6 or 7 MH
Penn Battle 3000
Power-pro braid 15-20lb

Other stuff may be lighter and prettier, but won't be any better necessarily.

I agree with Sponxx. I use the same setup for salt except I use a 2500 Penn Battle, but the 3000 would work jut as well. I like the battle for a spinning setup because you can use braid on it without having to back it with mono.

thank you guys. Exactly what I was looking for!