google the plant name with 'to buy' after it and then see what you get. I would go for a proper garden centre or on-line dealers rather than via ebay. better insurance if the plant is not up to expectations.

I would completely disagree with the other answer. Garden centres are very unlikely to stock the wild form of the Siberian Pine - they may have expensive ornamental forms but these are likely to be sterile and the chance of getting nuts is very low.

Try specialist online suppliers such as the Agroforestry Research Trust in the UK or Fruit and Nut in Ireland. Even if they do not list Pinus sibirica as a stock item they may have it, or be able to get it.