I can *highly* recommend Adam Hamilton of Hamilton Organics: email@example.com, 623-523-4528
If you want red wigglers, the local bait shops usually do not carry that type of worm as they are more of a garden/composting worm. Late last year I started vermicomposting and got the worms and the 'Worm Condo' from Adam. He's very helpful and a local small business person trying to make a successful business for himself and his family with his worms. And I have some awesome garden fertilizer happening in the back bedroom!
He also has some called Alabama Jumpers...bet your grandson would like these! Much larger and I guess they jump. He sells them to gardeners with clay soil because the jumpers, being larger, are good for breaking up the soil. Those worms are a bit more pricey than the red wigglers. Good luck.
Adam is out of jumpers and is rebuilding his supply. I'm too impatent so I ordered a small amount from TX. I've got a completely shaded North facing clay bed that I throw my pruning scraps into. A worm resort, so to speak.