I am in the same boat as you, looking for an under $200 red dot sight for shooting slugs and I have come to the conclusion that there may not be such a creature.
All of the reviews I have been reading online seem to be a mixed bag of reliability for nearly every brand out there. Utradot seems to be the most reliable and has a lifetime warranty. I was actually interested in either their Pan A-V
or the smaller Utradot L/T
The Pan A-V, is a made in Japan copy of the Hakko BED-35 MKIII Panorama. There are also a huge number of Chineese copies of this design, and none will hold up. I even had someone from NCStar, which is one of the companies that markets a copy, tell me he would not recommend using their sight (D4B) on a shotgun.
I also spoke to the owner of the company that does all of Ultradot's warranty work and he said that while the L/T is the more reliable of the two, he wouldn't recommend either for slug use. While they may hold up for a while, there was no guarantee that they would hold their zero over time.
I think I may have no choice but to wait to save up for the Bushnell Holosight
Which is the less armored version of the mil-spec EOTech holosight