The "willing to decant" notice implies that person will sell or trade a decant from their collection if you contact them. Personally I've found the decant list on basenotes pretty useless, and for women's decants or splits most go to other sites like MUA or PoL or they just buy them. The basenotes site owner doesn't even allow open trades or sales of decants here anyways though some quietly do so.
theperfumedcourt.com and perfumebay.com sell samples of Green Irish Tweed. No affiliation.