Yeah, but far and few. My first cap and ball was a Euroarms Colt Navy. It was rusted and pitted, but it cleaned up nicely. The finish was more or less intact, but the pitting looked like a snowflake pattern. I got that for $85 after haggling from $120 I think. At the same show, there was a brass frame Remington listed for $80 (seller indicating he will lower). It was perfectly functional, but dirty with grease. I passed on that one. At the show I went to last month, there was a Navy Arms (I forgot manufacture) brass frame, round barrel Colt Navy for $80. It was functional, but again, dirty with grease and minimal rust. The grips were a good bit oversized though, which leads me to believe it was a kit gun. My friend passed on that to buy a Mosin rifle as his first gun.
Around here, deals are around, just rare.
But yeah, there are the overpriced ones. Someone had a Navy Arms Remington for $270.