Unfortunately, teethers and teething necklaces must be tested as final products. We can't rely on supplier certs.
They are asking that price for each sample? I'd double check. If they are, shop around. UL Labs has a flat price per test, regardless of sample number. The tests are also very close in price, if I remember correctly.
As for the number of tests, yeah, that sounds right. Honestly, if this is a product that you sell a lot of, you might well want to consider going ahead. You will probably want to raise the cost of your necklace to help offset the cost of the testing. I think that $4.95 is on the low end.