The first printing was released October 24, 1973.  This edition is still in print, so some are much more collectible than others.  Prices range from maybe $15 (used VG+) to about $200.  A first impression would occasionally go at auction for $275-300 after LotR was made into films, but it was unusual and didn't last.  There is a great deal of misinformation about these floating around the markets.  The copyright date is often given as the printing date, and the material on the cover and slipcase is often mistaken for leather:  none were ever issued in leather.
 
A spelling error in the Dwarf runes on the cover exists on 1st, 2nd, and some 3rd printings.  All of these printings were ordered prior to October 12, 1973 - according to Hammond & Anderson (20,000 / 5,000 / 5,000).  Third printings were on retail shelves by February, 1974 (according to owner dated copies).  It seems that the majority of second printings were sold to lending libraries (when it is found for sale it is almost always ex-lib), so second and uncorrected third prints are less common than production numbers seem to indicate.
 
All printings up to fourteen have green marbled text block edges, though not all 14ths do.  I've seen some copies with light speckling (not giving a marble effect).  Only trade editions have the green decorated edges - book club editions and later printings do not.  Printing number is stated (see photos below) or indicated by a numberline through the 30th.  It would appear that the practice of numbering these was halted soon after the 50th anniversary.  It is reasonable to assume that the print numbers would be well into triple digits now.
 
The gold 50th Anniversary edition (1987) has a metallic finish to the boards and slipcase, with the decorations in green and red.  The trade anniversary edition has green speckled edges, like early printings do, but the vast majority of the ones found for sale (95%, I'd say) are BCE/discount editions;  blind stamped, with yellow top stain and three undecorated edges.  BCE's in fine condition are currently selling at about $20 (2009).  It would be difficult to assess value of trade editions, as the gold cover is actually both very common and extremely popular.  Most sellers fail to make a distinction, since the difference is not generally understood.  On those rare occasions when I've found one (and it's been a long while), it has sold almost instantly at $50.
 
In 1988 BOMC issued a large softcover using the same sheets, displaying the same ISBN.  This is bloody impossibly hard to find.  I've not been looking for it, but still... I do a fair amount of digging, and have not stumbled across one in nearly three years (2009).  There is very high demand for this due to its scarcity.
 
All variants of this ISBN have been sold by BOMC and/or through other discount outlets.  A serious collector wants a 1973 printing.  Anything with marbled edges is worth more than the MSRP of a new copy.  Just my opinion... any used copy too recent to have a stated printing number (except for the trade 50th Anniversary issue and the softcover), is worth about the price of a standard used book (half retail), not more.
 
The current list price for a standard edition is $35.  Though not so well built as the description and appearance seem to imply, they are very pretty, with much larger color plates of Tolkien's art than any other issue - scroll down for sample images.