You may want to look at the Vortex Strikefire as a lower-cost dot sight. It ain't an Aimpoint or Eotech, but not a bad value.
Now, I am always careful to state that my thoughts are my opinion. Try to make it clear I am not an expert. Don't know it all. Room for other opinions. Etc etc etc.
BUT
Do NOT buy a *** sight that looks like this picture. You will see the same design with about 10 different brand names stamped on. I would bet you $1 they all are made on the same crappy tooling at the same crappy plant in China. The quality and durability is dogshtink. You'd be better off rolling up a $50 bill and taping it to your rail as a peep sight. That way, when it didn't work, you could take it off, unroll it, and still have $50.
Not my opinion. FACT.
Good luck with your builds!