Coach,
I've done a hundred or so seam rippers. They sell well at craft fairs. I usually charge $5 to $9. And they're easy to make.
Go to Walmart and buy the blue handled seam ripper, I think it's 59 cents. The metal piece is just a press fit and easily removed from the handle. All of the red handled ones I have tried had the metal glued into the plastic handle and it was difficult to remove it.
Turn the handle 2 or 3 or 4 inches long, drill a hole to match the metal blade, and press fit the blade. If it's loose, use CA glue.
If you want to sharpen the seam ripper, strop it with a leather shoe string.
Happy turning,
txbob