Are there better and worse manufacturers of this effect? The prices are all over the map, from $7.98 to $20!

I would suggest to get the ones that are laser cut.

I would suggest coins from Johnson Magic or from Roy Kueppers.

Ray

Thanks guys!

I agree with Ray.
Todd

I ordered from Roy. Got the single and double fold quarters..
Read the thread on Roy a minute ago and got a bit nervous. Have a gig in march I want these for.

Roy's coins are impeccable. Make sure you inform him you have a deadline (make it two weeks before your real deadline) just to ensure delivery on time. He is a very busy man, but you will definitely be impressed with his products.

Ray

Out of interest is double or single fold better? I also want to get one of these but I'm in the UK so would be looking at getting a 10 pence version. I'd like to be able to do the coin bite and coin in bottle. I heard single fold is better for the former and double fold is better for the latter.

I just received a folding 50p and its a double fold. I'm finding it difficult for coin in bottle because it is easiest to just fold one of the folds in one hand than both, and it only works for one of the folds (the other fold will keep it too big for most bottles). So without detracting from the OP's question, I'd appreciate any help on this.