Posted 20 February 2016 - 01:40 AM
I'm not sure where you're located (I'm a lens technician in Melbourne Australia), but generally the cost to clean even mild fungus from a zoom like the 12-120 would be more than the value of another one, and yours looks to be pretty badly infected.
I wouldn't pay more than about 150 USD for even a pristine 12-120, and sometimes you can pick them up for less. If you got it off eBay I would try to get a refund. Fungus is one of the first things to ask about when buying old optics, it severely devalues a lens.
Mild fungus can sometimes be cleaned off, but more often than not it etches into the coatings, particularly if it's been left for a while. The surface under the front element of a zoom like yours is not too hard to reach, but the further in the fungus is, the harder it becomes, and the more time it takes. There's also the danger that spores can spread, some optical repair facilities refuse to deal with fungus infected lenses.