Some states are pretty uptight about buying, selling, or trading bear parts. I don't know about California, but I think Florida law now prohibits any commerce in bear products. I believe it's illegal to buy bear grease online and have it shipped here, for example. Some dealers know this and will not ship to Florida. As far as I know, it is illegal to buy or sell bear parts or products within the state, too.
With all of that said, claws can be found for sale, if it is legal for you to buy them.
Moscow Hide and Fur has black and Canadian grizzly bear claws for sale. Large black bear front claws are priced around $125 each (not a typo), and single grizzly claws are priced from $300 to $500
each. I see they have a full set of twenty grizzly claws for $4500.
Chances are your boys will need to settle for imitation claws of some sort. If you can find a copy of Ben Hunt's
Indian Crafts and Lore, he had a pattern and directions for carving and finishing claws out of wood. There is historical precedent for this... a Cheyenne necklace of wooden claws with Little Bighorn associations was recently up for auction:
Yellow Horse's Carved Bear Claw Necklace
I think faux bear claws were more commonly made of horn or antler, though. This Crow necklace (from
Cisco's Gallery) has claws carved from mountain sheep horn:
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I would recommend that you check out Volume 44, No. 2 of
Whispering Wind magazine. The entire issue was devoted to bear claw necklaces, and included articles on making authentic faux claws from hooves and elk antler.
The easiest thing to do might be to get the ready-made plastic or resin claws. The black plastic ones are still available. They are cheap, and they look it. However, I had a set of them when I was a kid and thought they were pretty cool at the time, but I doubt a 14 year old would be happy with them. Painted resin claws make the best replicas, and some of them look real enough to get you in trouble. These are available from many of the Indian craft suppliers, but
Teton Trade Cloth may be your best bet. Their top of the line is a set of forty graduated claws that are absolutely realistic, but the cost is $633 for the set. However, they also have a set of forty pretty nice plastic claws for $40... a dollar per claw. These will need to be painted to look their best, but Teton Trade Cloth has a blog post that explains in detail how to do this, and additional information pages to help with assembly of the necklace. Might be an interesting project for a motivated teenager.
Good luck with it!
Notchy Bob