Well, just because a product is a replica of another successful product, it doesn't mean it's of poor quality.
It can definitely be equally good in some cases. Now, back on the main subject, if you want the temperature to be 100% accurate, you'd have to calibrate it (regardless of whether it's analog or digital!). And doing so isn't as expensive as you may think.
You could just get the TM902C+PK1000 (digital thermometer+a high temperature probe) and melt some solder onto the end of it.
Both should cost you around $25 combined. Anyhow, if you wanna turn a knob, get the Weller WES51
But if you wanna save some money, get the Bakon BK950D (It has plenty of positive reviews, especially on Youtube)
You could get it for $25 from Gearbest:
http://www.gearbest.com/soldering-supplies/pp_363024.html?wid=21And you could also get a pack of tips for $10-13 from Banggood:
http://www.banggood.com/search/t12-tips.htmlEither would get the job done quite well.