I'd like to work on my grip more. Would a cheap gripper from Wal Mart or Dicks (or for that matter a tennis ball) be good enough or should I pay some extra money and get Captains of Crush or Iron Woody grippers?

Someone posted the exact same question about a week ago. Use the search function and you'll find it

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What lies behind us and what lies before us are tiny matters compared to what lies within us.

Training Log

One of many results from using the search function.
viewtopic.php?f=1&t=52579&p=695362&hilit=gripper#p695362

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Suspension Trainer Thread
To the Trolls: Since you seem to know something about everything, can you tell me what the biomolecular density of an atom is?

Everything you need should be in the links above, but yes, you should get some good grippers.

If you never train your grip, a sporting goods gripper might be worthwhile to get started (get a cheap one, you won't use it for long unless you want to see how many hundreds of times you can close it or something), but that's about it.

An Ironmind Trainer would be a better start.