I fished with that method a lot last year, particular when sight fishing for bass cruising the shallows and/or during the spawn.
I always just used a medium or large split shot - never bought any specific "drop shot weights". You could also beef up the weight to a regular drop sinker if fishing in current.
I recommend tying a little overhand knot at the tag end of the line, and putting the split shot above that. If you don't, you are guaranteed to lose the weight on the first tiny snag you hit.
I generally fish drop shot rigs in relatively clear water, and use green pumpkinseed 6" worms rigged with the hook going in about 1/3 of the way down the body (but still weedless). If you are sure you're free of obstructions, you might want to try leaving the hook exposed - "wacky" style.
I generally use about 8" of tag line below my hook for the weight, but you might want to experiment with that.