correct all the facts needed are there - the customs declaration is irrelevant. First both agreed and second no way a customs person in Ukraine would ever know whether a knife is worth $100 or $1000 - that's just not going to happen - think about it.
I cannot speak for Ukrainian customs but I am well versed with customs practices here in my own country, as well as the UK.
Here in South Africa, proof of payment may be requested by customs if they are suspicious of the value.
They send you a note asking you to appear with your proof of payment. They then open and inspect the package in front of you. If they don't like what they see or your paperwork/explanation is not in order, they refer it for investigation and then the fun starts.......... Customs here in SA are remarkably well versed in Google and most things show up in seconds with their values. There is no reason to think that customs in the Ukraine are any less adept.
There is little doubt in my mind that this entire affair could have been avoided had Gosh shipped the package correctly and not opened a thread falsely accusing SaviC of being a scammer.
In my opinion Gosh should refund SaviC in full and if the package appears SaviC should do the right thing and pay him in full. I have said this in previous posts.
However as Karda has pointed out, both the buyer and the seller agreed to mis-label and undervalue the package contents. So there is a chance that this action has caused the delay or seizure of the package.