Really more of a question of curiosity because I've never seen a KofK ad before :0 I'm sure it has been considered before, but I guess it's pretty expensive?

(off-topic question but I forgot if by the time the trial period expires can we adopt the Knuffel we picked or do we have to restart with another Knuffel?)

There is really no set price. If you want to advertise for example with google ads or on Facebook, you can determine your funds yourself. With Google Ads you basically set a limit to how much you are willing to pay per impression or click and the individual sites that host the ads determine what kind of offers they are willing to accept.
If you want the ads to have some kind of effect, you probably need to spend a few hundred $ though. We tried ads in the past, both with Google and with facebook, but apparently not with enough funds to really make a difference.

Ohh I see. I guess it is a difficult demographic because you're kind of appealing to a crowd that might not even be familiar with forums like this :0 I remember reading before from VPL (before it shut down, bless its soul) that sites like this usually appeal to a particular audience that has a history of doing virtual pets, forums, etc. Is it, perhaps, more expensive to advertise to currently alive virtual pet sites and forums like Flight Rising and such?

yeah I saw the "Adopt permanently" option under his page after a while xD thanks for answering my question~