Forget wasting your money on a dial indicator (especially a junky cheap one), unless you just really want one? If that's the case, there's a difference between a dial indicator and a dial test indicator, and for checking runout you want the later. Roller tips are never used on a DTI. Do a little research or try to find a machinist to give you a crash course before you spend money on something like this.
If you really think something is wrong with the driveshaft take it to a proper shop and have it checked for straightness and balance, that's what's critical, especially at high rpms.
If you are just trying to figure out a vibration, you can do so by putting the car up on jackstands and running it. Be very careful securing the vehicle. Tires/wheels are the usual culprits, but you can take them off once you've eliminated them and then proceed to the driveshaft test. Make sure you remember to put the lug nuts back on to hold the drums tight if you don't have rear discs.