Good grief Grivna, I have not seen this post for ages and that 15kopek-1zlot of yours is a shocker! Thanks for showing.
Mariah, like what Grivna has mentioned, excellent condition can vary from people to people, like Bluesfil example might be excellent to you as you might factor in the age but condition like his might be suprisingly cheap at times like 30USD if you are very lucky. However coin condition like Grivna's is QUITE uncommon so be prepared to pay a high price for it. I personally like the huge 1.5ruble-1zlot as this is a perfect 1 ounce monster coin. (weights 0.1gram less than an troy ounce though)
Like like what Grivna said, post a picture and we can give you a better estimate. Welcome to coinpeople by the way