Post your wants (within reason), or if there is a particular item in demand, we might have a single topic for that figure.
If you can help out, contact the person. If you are looking for something and one of the members offers it to you, make sure you know them well enough, or can get someone to vouch for them, or better yet pick up in person.
(Disclaimer) All transactions are at your own risk, and this board or its staff are not responsible, so be careful who you deal with. Most of us here are reliable folk, but it just takes one to ruin it.

Also, if you find an item that is high in demand but can't afford to buy it, post here that you found it, but mention that you will only reveal its location to those who contact you (who are local).