Thanks to all for the suggestions. I will check out all the names that folks have mentioned and will let anyone who cares know what I decide. No particular problem with auction houses per se, that's where I procured most of the ones I have. Didn't appreciate the one experience with the flawed Columbian, but that was from an auction house that is now defunct. I was just looking for any recommendations for reputable dealers as alternatives to auction houses, given the price I will probably have to pay for these items and the 20% buyers premium (give or take). Maybe the dealers will turn out to be just as expensive, I don't know, was just looking for other collectors' actual experience with specific dealers to give it a shot.
As far as
ebay is concerned, I have no particular problem with it as a venue to acquire material when it makes sense. I use it to buy inexpensive covers that fit into my peculiar collecting specialty in postal history. For some obtuse reason it didn't occur to me that some of the well regarded dealers dealing in more expensive material might happen to use
ebay as well as a conduit in addition to direct contact with collectors, shows, etc. If so, then fine, but first I need to identify them, become comfortable with them, and, if I like what they have, purchase the material in the way that makes the most sense,
ebay or not. I just would not be inclined to use
ebay otherwise to spend the kind of money that I envision spending here for the reasons that a few other posters such as cjpalermo put it more eloquently that I am able to.
As far as the notion that some folks might be inclined to refrain from revealing their best sources of material, that wasn't my notion - one or more other folk(s) mentioned that in an earlier thread some time ago in this forum. So I just drew the conclusion that it wouldn't have been mentioned if those someone(s) didn't have a pretty good idea that it might be happening.
Thanks again - didn't mean to stir things up but if some of my comments sparked some blowback and lively discussion, so much the better I guess for a more interesting forum.