i'm going to start performing my own TBSes. Need suggestions for a manometer. i'm not going to make my own. any recomended makes. if i go electronic/digital anything i need to be aware of regarding the specifications of the unit? like max pressure, type of measurment it can take, or whatever? i'm not familiar with them so i don't even know what to look for. prices range from mid $100 to almost a grand. don't know which would be too little and which would be too much.