Trigger control practice setup

[StPatrick]

While at CHMR on Sunday, I had a chance to meet a nice fellow who was into competitive shooting. His warmup routine involved using a Smith 617 with a red-dot sight to practice trigger control, and he explained that keeping the dot on target through the entire pull (he used the DA) was good practice.

He was nice enough to let me try it, and the utility was immediately apparent - with that setup, there's no head-scratching "how did that flyer end up there?" moments. The experience made it clear that my trigger control needs work, and this seems like a fun way to practice.

So, first, is there a more economical alternative to the Smith? If so, how much am I giving up in the smoothness of the trigger pull?

What are "good enough" red-dot sights for < 25 yard shooting that could easily be mounted to a revolver?

Thanks again, your input is always appreciated.