for someone to be a guest, or a member, or a gold member?

Are there platinum members?

 

I guess you missed Cthree's thread about voluntary subscriptions? Basically, a guest is a forum "registered" person who has not purchased a subscription. A member is one who has purchased the basic subscription ($20.00). A gold member is one who has purchased the higher subscription ($50.00 +). Each subscription level comes with increasing "perks". These are discussed in that thread. Once the "search" gets back, it will be easier to find. (You can check "site info" for it.)
ps. There is NO platinum.

 

Check it out here:

https://www.s2ki.com/trade/productlist/1/