Bought the Dr. Joel Versatile Prostate Simulator last week - and give it a big thumbs up. The curve is well designed and the vibration variations are lots of fun. 10 different vibe settings including a steady vibe and various combinations of slow pulsing types. Have used it a few times during some long edging sessions. I've mixed up the vibes - all are good - finding the steady vibe is best for when finally release my orgasm.
You feel the vibes throughout the toy - so the part that comes out under your balls feels nice. Cost $40 at an AMAZING store - well worth it
Only drawback - and it's minor - is using in for a long time while sitting - it does need a little adjusting every now and then - my Vibro Play toy is still the best for a long sitting edging session (it's not curved and only has one vibe speed but it just sits there and does it thing) - pic of that is below the pic of the Dr. Joel. The Vibro Play one is only $20 - so if this is your first time getting a toy like this - maybe try that one first. It's also good because it gets a bit wider from the tip to the base - which feels nice :)