Then you certainly know that the market for .is domains is extremely tiny.
There are very few reported sales, a few LL have sold but there is no regular market. I myself have had a couple inquiries on LL.is domains.
I think that 1-letter domains are trophy domains. I own a couple and I am still waiting to offload them So I think they are overrated by domainers.
I don't think you will easily fetch more than low $,$$$, if you find a buyer in the first place.