When I started my vegetable garden in south Florida many, many moons ago, there was not a single worm in sight.
So I paid a neighbor's son a dollar to find some for me. He came back with about a hundred worms from the nearby woods. I had horse manure dumped on that garden each summer, so it didn't take long for those few worms to turn into hundreds, then thousands.
I suggest you dig around under the leaves in a nearby woods or park and bring home any worms you find. Providing you give them good organic soil to breed in, you will soon have plenty of worms.
Incidentally, compost worms are different to regular earth worms. As far as I know, each will not live in the other's environment. You might want to check on that if you are looking for composting worms - known as red worms or red wrigglers.
Go get yourself a couple bales of straw or hay. Take a spot anyplace on your property and create an area with six inches of straw or hay mulch. Water it good until all the mulch is wet. Keep it damp between rains. By mid summer you will have all the worms you want. You can get the same results of using ground wood as a mulch in your flower beds. No one needs to purchase worms.
If you have gardens that do not seem to have worms those gardens are way short of organic content. Work organic material into your soil. Add leaves and plant a cover crop this coming fall. When the soil is right they will come. You need not buy them. Even if you do purchase them they will not live or stay if the organic content of the soil is not dealt with first.
Early this spring you could arrange to till in an inch or so of raw manure. The key word is "early". If you can not get it in by March or April you would be to late to do it right this spring.
Coffee grounds are great additives to any soil. Worms love them. However if you think you have none or few you still need to build your soil. As you build the soil's organic content they will appear to help make your soil even better.
When I first moved here, my yard was bare compacted chalky clay - no worms. The morning after a rainstorm, I would walk around the block rescuing worms off the driveways of yards with older established landscaping. I seem to have worms now.
sorry im doing a school project with my daughter and it needs to be done in march and cincinnati has 21 inches of snow on the ground. so we went with a solar panel expt. instead but thanks for the suggestions