What's the cheapest yet most reliable guide camera I can buy?

[Trippelforge]

I am finding out fairly quickly that my new AVX really needs guiding. Which is a let down, but supposedly with guiding it can perform very well. The problem is that I have never owned one before, and I am very low on funds so I am trying to find something reasonable. I know "reasonable" is relative, but I need to know how low I can go, yet get one that's still reliable. I guess that goes also for a finder scope itself... which I just remembered. 

Thanks!

[ONIKKINEN]

Hard not to recommend the 120MM for this purpose.

With a 50mm finder/guider you could still be under 300€/$ so for budget applications this would be the setup to go for.

[skybadger]

Find a second hand lodestar, large pixels, rock solid. Highly sensitive.