Opinion needed on Riverfront Castroville Home/Land in Flood Zone

[Seini Vi]

I have 6 acres of riverfront property in Castroville, TX less then 2 mins from town square. Some of you may know that San Antonio is expanding towards Castroville with all the home communities coming down 90 and the town is now having a large home community built in it starting at 450k+. My land has the Medina River flowing through it.  It is in the flood zone, has a 1000sqft home built on concrete slab, a garage, horse barn, water well, and unattached building which was being converted into airbnb. I've had 2 real estate agent groups come and both suggest different starting sell price: one at 500k, the other at 200k.

Both groups were interested in partnering up to turn the property into an airbnb rental investment.  

We've had 2 locals offer 120-180k, their given reason was "no higher because it's in the flood zone and isn't worth anything".

There is also another property very similar also in Castroville TX  (8 acres, river front, 1200 sq ft home in the flood zone) that is listed for 1,200,000, though that's been sitting for nearly 3 yrs now.

  A neighbor whom I share an easement with (who is also in flood zone with riverfront ) rents his property out for party celebrations/camping/etc. and is currently building a 500k home on his property.

I would be happy at selling at $650,000 to an investor or to anyone really. My thoughts are the town is growing and if there are people willing to buy one of the new houses in the home developments for 450k then a 6acre home on riverfront for 650k isn't so bad is it? The property can be compared to Gruene River Road in New Braunfels.  

An investor could put cabins on the property or a home builder could put at least three more houses on the property and sell them individually as river front homes. 

I've tried to reach out to land acquisition at some of the known home building companies in San Antonio but having to find contacts & being sent straight to voicemail seems to be an never-ending loop. 

I'm in need of opinions. Am I delusional for thinking I could sell for this price or am I being reasonable ?