terky,
I hate to say it but unless you know how to assess the ads and the sellers, e-bay is a good place to get screwed. Once you learn the right questions to ask and the red flags to watch for it can be an excellent place to shop too.
If the seller is really reputable, he/she will answer your questions if you seem seriously interested and at least basically knowing what you are discussing. Most of them do NOT want to take their time to educate you about their product, but some of them do and if you find a seller like that remember him when you need to buy things.
EVERYONE --REMEMBER THAT A SELLER'S KNOWLEDGE CAN BE EVEN MORE VALUABLE THAN HIS PRICES. IF YOU FIND A SELLER HOW IS KNOWLEDGEABLE ABOUT GROWING MJ AND WILL TEACH YOU WHAT HE KNOWS, THEN YOU OWE IT TO HIM TO BUY FROM HIM UNLESS THERE IS AN UNREASONABLE MARKUP.
Happy New Year and GREAT SMOKING!