Coin shows are just vague as to how good they are. Also, they change by area. I've seen coin shows come and go due to no attendance and I've seen some so crowded it is difficult to walk in the aisles. By me there are a minimum of 3 shows a Month and used to be 4 a Month. One closed due to little attendance but possibly due to location. You really never know. There is one near me every Month that has always had from 80 to over 100 dealers. There is a 3 day coin show coming up on Sept. 22, 23, 24 as well as one on Sept. 18
How many customers and dealers, no one really ever knows.
To rent a spot at some, it would cost about $50 a day. At some larger shows, like the ones at the Rosemont, Il. Convention Center, a table could cost a few thousand dollars.
Best thing for you to do is make a list of coin shows in your area, go to them and check how they work, their costs, etc.