I like the Vernet Classic http://www.penguinmagic.com/p/116
. It's inexpensive but not cheap. This is one of those props where it's a lot more important what you do with it, than it is how much you spend on it. If you have larger hands, you might want the jumbo version. But I use the regular.
This reminds of a time, many years ago, when I clutched my Christmas money and went to Al Cohen's (Al's) Magic Shop in Washington, DC.
I asked Al if he had any thumb tips and he looked at me like I was from Mars. "Of course I have thumb tips, I have a whole drawer full. What do you want?"
I told him I was looking for one that matched my pale skin tone, and he scoffed again. "If you're concerned about your skin tone, you have a layman's concern. Do you want to be a layman the rest of your life?"
He went on to show me about a dozen ways to hide a thumb tip, all in the course of about 90 seconds. His point was that if you have the right technique, it shouldn't matter what kind or color you use.
He then said, "The last thing you want to do is show your hands and say 'Look, my hands are empty!' Why should you call attention to your hands being empty? Of course they are empty. If you believe it your audience will accept it."