I don't actually know of any low-cost options, as we've gotten our rabbits from shelters (other than Nala, who was spayed by my vet when I still lived in San Antonio)... but I definitely know about exotics vets in Houston!
I was happy with the (emergency) care received at
Gulf Coast Veterinary Specialists, even though it was too late to save the animal brought there all three times we've had to go (sugar gliders and finches are even better at hiding illness than rabbits and necropsy results confirmed that there was nothing GCVS could've done to change the outcome). I was NOT happy with the bill, however. They've really got the market cornered as the only 24 hour exotics vet in all of Houston and even their non-emergency/normal hours prices are really steep. Don't go to them for anything other than an emergency.
I got a quote once from our vet at
VCA Spring Branch (Gessner and Long Point; near I-10 and the beltway) that was around $230 - I was debating having her fix Alice because I was wary of bringing her back to the shelter to be spayed (she was too small when adopted for the surgery) due to the fact that they wanted to keep her overnight. We had some financial issues before following through on the spay, so we ultimately took her back to CAP for her spay rather than VCA. I love the exotics vet at VCA, though. I've also used
Animal Medical Center of the Village (Kirby by 59) on numerous occasions for sugar gliders (mostly because they're the vet for a BIG sugar glider breeder in Houston, so they treat and neuter tons of sugar gliders), though I've never taken a rabbit there. They took wonderful care of our glider Hobbes when he had enteritis. If you ever go there, tell Micah 'hi' for me! (He's the awesome cockatoo in the lobby.)
Pet's Paw in Conroe also has an exceptional exotics vet. We live in the Woodlands now, so that's where I ended up when Nala stopped eating last summer. The vet was *wonderful*!! She quickly determined that Nala's issue was spurs on her rear molars and was able to confirm my suspicions that she's got a touch of osteoarthritis in one hip. She gave a very thorough full-body examination and her bedside manner gets 5 stars from Nala! Nallies needed dental surgery and I was quoted a price quote of $280... they said that was the maximum estimate; it might come out to around $30-50 less depending on how easy her mouth was to navigate and how long she had to be kept under anesthesia. When I picked her up after the surgery, they handed me a bill for $149! The vet said her mouth looked really good afterward and she didn't even need to take any pain meds home. She's been eating like a champ ever since.
You mentioned that you asked the Humane Society for a referral and struck out (btw, darn you for prompting me to look at their website... didn't even know they had rabbits... now I'm talking myself out of wanting to impulse-adopt "Ginger" because OMG, CUTE!)... have you tried the
Houston SPCA (by 610 & I-10 on the west side) or
Citizens for Animal Protection (in Katy)? CAP seems to deal with rabbits more than other Houston area shelters and unlike Houston SPCA, they allow bunny-dating; they're very rabbit savvy and big on owner-education for those looking to adopt rabbits. Their vet did an awesome job with Alice's spay, which we celebrated by adopting Barnaby and Harley Quinn (taking us up to 4 rabits)
. That shelter has a very "hands on" feel when you visit and I feel like they're probably most likely to be able to connect you with low-cost services.
Edit: Out of curiosity, what vets quoted you the $500+ prices?
