Between Craig's List and E-bay, it took about 5 years to finally kill the photo swap meets in the Portland area.
Meets became a few dozen sellers with a lot of old junk that showed up with mostly the same junk year after year. It was still fun to go poke around, but neither the organizations fronting the meets nor the sellers could make a buck. Sad. We had about 25 years of continuous annual meets, even had two competing meets at one point.
I know there are ones in Watertown, MA a couple of times a year, but I don't know of others. If Whitey checks in, he knows the site and timing for the ones in MA and might know how to find out if there are others. I got a 6x9 Zeiss folder for about $30, IIRC.
Unfortunately, Whitey knows only what bdial knows at this point. The PHSNE website says that their spring show this year will be May 3 & 4 (in Wakefield these days, not Watertown.) Barry is also correct in his estimate of costs there. High interest items go for a touch more than the same on a good website, but there are deals to be had and folks to ask questions of. More than anything else, it's fun.
There is a monthly show, I believe, in NJ, but I'm not sure of the details. Sorry.
Whitey- I get a flyer from the show in jersey but as usual I'm nowhere near my house right now. I will post the details when I return on Dec 8 it is still a pretty good show. there is a great filter guy and some other regulars who know their stuff. I found an 8x10 which I sold to Jim Galli and a bunch of other stuff. it runs on the second sunday of each month...
I bought all of my stainless steel darkroom gear at the 2nd. Sunday Wayne, NJ show. That was a few years ago. E-bay has killed it off and the show is now about a third of what it once was. Still the place to go for filters. You never know what you might find. It's just a lot harder to find stuff now.