Buying Metallica vinyl can be a very confusing affair, and it is very important that you understand the chances of buying bootleg material.
Much of the basic principles apply to vinyl from other bands, but i know metallica, so that is what i will talk about here!
Metallica is a popular band, especially amongst people who collect vinyl records, and as such, there is a large quantity of bootleg mateial available, and much of it is available on eBay.
There are a few sub-genres of bootleg vinyl records when considering Metallica.
The first type consits of concerts recorded onto vinyl. Most of these are of older shows (with digital media and CDs being cheaper and more readily available these days, newer shows are rarely pressed to vinyl).
These vinyl records, while expensive and unlicensed, are much sought after and cherished; be prepared to pay upwards of $50 for one of these. Concert bootlegs on vinyl may have widely varying sound quality, and widely varying quality cover artwork, but almost all of them are worth buying.
The second type consists of counterfeit Metallica recordings. The most common are picture discs. There are only a few official picture discs available (ie Kill 'Em All, and a few singles). Most albums are not available as picture discs as official releases, because the entire album does not fit on one record.
Other vesions of these include "Label copies" of albums etc. A general rule of thumb - if the plain everyday version of the album is available on 2 vinyl discs, then there won't be a picture disc or "Label Copy" available, as Metallca does not release any albums in any form that is incomplete.
Again, these items are still desirable, especially the older ones. Many are manufactured in Mexico, Korea, Canada, and Germany. The Mexican ones are less common (ie more desirable), and the German ones are generally of better quality, but are more common (this less valuable).
The third type of bootleg album type is poor quality knock-offs. This is exactly what you would expect - porr quality vinyl used, vinyl from another band with a Metallica label put on it, photo-copied album sleeves etc. These should be avoided at all costs.
If you are serious about collecting Metallica bootlegs, the first 2 types should be of interest to you. The third should be avoided like the plague.
An excellent way of identifying these is by sight - since we don't have this luxury on eBay, asking questions is the only way! to know what questions to ask, check out the site Metallipromo.com - they have information on just about very vinyl of Metallica ever released - if you have found a Metallica vinyl on eBay, then search for it here. Find details of identifying marks etc, and then ask the seller a question.
Following this buying guide, you should always end up with an item that you can identify, and you won't feel any disappointment about getting an item you weren't expecting!