I currently have the drag specialties speedo and a non-name brand tach between my clip ons. The drag specialties has worked really well for the 600ish miles I have since installing it. The previous speedo vibrated itself to death. The need return spring detached and after attempting to glue it back it didn't work. Both gauges were 30 to 60 bucks if I remember correctly. The tach has held up well and it has probably 2000 to 2500 miles so far but the needle does bounce a little after 6500 rpm; though that's likely a cable issue.
Its definitely up to your taste. I'll say to be careful getting something that is definitely vibration resistant, but given the inherent risk with those gauges you may want to just spring for something a little more expensive but with less or no moving parts. If I were to do it all over, I would consider getting a speedo/tach all in one and go electronic or GPS.