The first person to tell the seller "I'll take it!" unambiguously will probably get it. A seller can sell to anyone he pleases but in the interests of fairness and tradition, generally goes by the first clear acceptance of his terms.
PMs are Private Messages, kind of like Bladeforums internal email. Only paid members get to use PMs. So if you want to buy a knife, post in the thread "I'll take it" and
click on the seller's user name to get a menu to select "View profile". The profile will link you to a form to email him with your acceptance, your name, address, how you will pay him, etc.
You can use the
bold information above to email him with questions also. Just remember, asking a question is not dibs on the knife.
* ****** **** ****** *
As always, post here in Tech Support with any questions on policy, or email moderators (me

) if you like. Tech Support is best because others can also learn from your question but sometimes people don't want a public debate on a problem.