I dont understand

I have no idea what "constand" is. I'll probably need the whole quote on that word.

"I am all set" is the same thing as "I am ready".

A mystery lot, I would assume, is a group of unknown items. In an auction, you can bid on (offer money for) single items or groups of items; those groups are called "lots".

<Uriel :A mystery lot, I would assume, is a group of unknown items<.

Actually the "mystery lot" on eBay I gave a link before it's a bunch of mystery books, mystery audio and comic books.

Ah. I was thinking of buying a pig in a poke, or one of those deals where you can buy the entire contents of an abandoned storage space cheap, but sight unseen.