Although I am not a collector of David's work, he certainly does have his own unique style, as most of the Lottons do. Some of the heaviest and most beautiful (in my humble opinion) glass was made by John Lotton when he was still blowing glass. I do not own any of his great pieces (although I do have 2 of his free form sculptures that are in the Lotton book, and think that these will be important pieces down the road), but a friend of mine who collects Lotton glass has one of the best collections of John's work that I know about. Many of the pieces are shown on my club website, under the "Lotton Glass Study", "John Lotton Study" area.
Personally I only collect the works of Charles, but I can appreciate all of the Lottons works. The Lotton studio has a website (as you mentioned above), and their gallery downtown (Chicago) also has a site that actually gives the retail prices of the pieces they list. This site can be found at http://www.lottongallery.com
Remember, most of the pieces that you see on either of these sites (and other sites that I've seen) are showing glass that has been made in the past year, so they do not give any examples of the older pieces. (that's what my club site is for...Hehehe!).
As far as Terry's early beer bottle piece, it is certainly a historic piece, if nothing else! Some of Charles early works were made from whatever glass was free! Besides beer bottle pieces, there were also pieces that are known as "Fresca" pieces, which were blown from the green glass that came from Fresca bottles. And in 1974 and 1975, he used milk of magnesia and beer bottles together to make pieces that are known as "Persian Inlay". Here is what a piece of Persian Inlay looks like: