How long does $5 soldering irons(that plug directly into mains) last?

I used to buy similar cheap soldering irons from Radio Shack and they lasted several years, but I don't solder every day. I would recommend buying one from someplace "reliable" that sells replacement tips.

And, get a stand for it. They are usually lightweight and they can end-up "moving around" and burning your worktable (or whatever else).

Now, I have a Weller with adjustable temperature that I paid about $50USD for.