There isn't a guide out there that I'm aware of however making one sounds like a great idea
I'm guessin you're talking about ordinary quad premiums here -- of course the same kind of rules regarding pronounceables and rares regarding LLLL.coms apply here.
The biggest determinant of the value of an ordinary quad premium at present on average is probably the exipiration date. Most sell in the $2-$10 range with almost all selling under $20 unless they have something special going for them such as pronounceability, traffic, rarity, etc.
stub said:
Where is the best guide for LLLL valuations. I'm trying to find out if 4 Premium Letter .nets are worth anything?