Hi David, as others mentioned, no response is just plain rude, and that has not been my experience here. Sometimes you will see the seller finally get around to marking the item "sold" shortly after you e-mail them, which might indicate he had already sold it before you responded. You should still get a response, but everyone does not operate that way. Just hang in there, and be very sure you are clear in your offer. In other words, if it is an item you really want, from a well-regarded seller, make it clear you are making a firm offer, and not just kicking tires.
To Mrjstark, I must take exception to your profiling everyone with feedback scores over 300 as "in it for the money," and those with scores over 100 as being insensitive to newer members, or that they "don't remember the day they started." That is just plain not true here and paints a distorted picture for David. One of the best things about this site is the wealth of information offered to the newer members by those with more experience, and even by some folks in the industry. Also, many with higher feedback scores are not in business, but have simply been at this a while, and enjoy trying new equipment. My current feedback score is over 300, and I have lost money overall. However, I am willing to sell for similar prices to those at which I purchase, and sometimes for less, just for the opportunity to upgrade and to try new stuff. In the meantime, I get to enjoy using the equipment I purchased.