Over the years, I've picked up two Tasco red dots off ebay for around $40 each, so if you have some time, you might find a deal.
Also, regarding that leaving the red dot on....... Well, I normally don't, usually just switch it on when I set up on a bird. In Alabama a couple of weeks ago, a bird walked in on me unannounced, and unexpected. You guessed it, when I brought the gun up, no red dot. Bird took off before I could fumble and get it switched on. Could have used the bead sight, which, on mine I can just see under the mount, but I didn't think quickly enough. I suspect I'll be leaving mine on all the time now. Neill