Red dot sight?

I have used a little $20.00 sight on several walk around guns with great success. Sight it for your optimum yardage and you're usually good for most situation. I am assuming you know your gun's ballistic trajectory. The only major drawback is if you have an astigmatism then the dot will always be blurry. I have and it is however it still works if you ignore the fuzzy dot. Great for walk and stalk, rats, rabbits etc.

I never felt the need for a really high dollar sight and I know there are really good ones but this works fine out to 50 yards. 

Have you heard of the seeall sight? Its not a red dot but is pretty sweet and takes no batteries. Worth a look. 

on the Seeall rear sight, I bought one and took it out of the box and put it back in the box and you need a weaver mount to attach

besides a red dot there are reflex type sight they are cheap, under 20 bucks

I have 3 Ohuhu like this

https://www.amazon.com/Ohuhu-Green-Reflex-Sight-Reticles/dp/B00YRIHYIW/ref=cm_cr_arp_d_product_top?ie=UTF8

they also need a weaver mount or adapter

these red dots are very good but they aren't free

http://www.ultradotusa.com/index.html

so my advice buy a cheap reflex sight and try it and go from there, one thing they do have is a better field of vision, a reflex sight that is

so back to the Seeall rear sight it is well made but it could be a love it or hate it product and I'm neither, it is just odd to my eye

Septicdeath, it depends on what you want to do. UltraDot is a red dot of choice for a lot of NRA Bullseye shooters. You can get it in different size tubes and even with adjustable MOA dot sizes. Best of all, it is made in Japan and not China. I have 4 or 5 of them in different iterations.

If you are looking for something more field friendly, check out the Aimpoint Micro T2. Wicked good and wicked expensive. I have one mounted on an AR 15 with a quick detach mount from LaRue. In my opinion, the best you can get.

Also field friendly are the Eotech holographic sights. I have one of these on an AR 15, but like the Aimpoint better.

None of these are cheap, but would work well on an air rifle if you do not need magnification.

Mike

I have 2 SigSauer Romeo4 sights that are C model (C model was solar powered). They have functioned perfectly across several platforms from shotguns to rifles. Even had one mounted on my HW44 until I scoped it. Nomenclature has been changed on the line in the last few years so I think the current match is called a 4S for solar. Mine was available with selectable dot (2 MOA) or dot/circle reticles, 12 brightness levels (IIRC), and auto shutdown that works faster than I've been able to detect and allows long term storage. I believe the newer models have more reticle selections available but not certain of that. Battery life claimed to be 100,000 hours for the solar and 50,000 for the non solar models but who knows (haven't changed a battery in one in about 2 years now). I would not hesitate to purchase the same model again and I would expect similar quality from the current line. I have no experience with Ultradot or Aimpoint but both are highly regarded.

I would suggest getting an inexpensive one to try to see if you like them overall and if so then get the best you can afford.

 Bushnell TRS-25 is another choice. Comes ready to mount. I picked mine up for $56 on Amazon, though currently they are $79.99. Might can hunt it down cheaper. Honestly I haven't had it and used it hard enough to have put it through it's paces, but I like it so far.

I'd have popped a bit more for a Holosun 403...but why? I spend enough...this isn't my battle weapon.