The danger of cheap non-temperature regulated soldering irons is that the cheap soldering irons go from too hot when starting to solder the joint to too cold from cheap tip materials with poor thermal conductivity. This leads to joints that have cavities and are improperly flowed, especially a problem for radio frequency or high speed digital circuits. Cheap soldering irons lead the newbie or even the experienced user to burn parts, lift PCB traces off the board and get so hot they are very uncomfortable to hold. Often the cheap irons are not grounded, so you could be zapping the circuit you’re trying to fix.
For the beginner, there are $40 soldering stations available from reputable online sources–checkout the reviews or YouTube to get a better sense. For me as a life-long electronics guy, I went straight to Weller (Hakko is good, too). I strongly recommend the Weller WES51 temperature controlled soldering iron for those who outgrow the use of the local maker-space or borrowing a friend’s iron. I emphasize the temperature controlled part because even the Weller WLC100 does not have closed-loop temperature control.
Many things we solder these days are of small size and delicate, so you don’t want to just guess at the temperature you’re using. The Weller WES51 is rated at maintaining the tip +/- 6 degrees Celsius from the setting. The WES51 has an analog temperature dial, which is close enough even with surface mount components, as you see in the photo below. It’s hard to see due to the focus, but the new white cap at the center of the picture soldered in like a dream, using the optional 1/32" tip.
For about 50% more cost you get the digital temperature readout Weller WESD51. We prefer the analog WES51 because one can change the temperature setting more quickly on the WES51 (just spin a dial vs. push and hold button on the WESD51), and it’s not necessary to have a perfect temperature setting or to lock the setting (perhaps something a factory assembly line would do).