I just rinse new plants under the faucet when I get them too. I bought a few of those foil meatloaf/bread pans at the grocery store, and I fill that with some water, add a few drops of dechlor, and soak the plants in there for a few hours. Sometimes the little snails aren't apparent right away, so after a few hours in the pan, they seem to come out. I pull off the snails, rinse some more, and run my fingers up and down them too, hoping to dislodge any snail eggs. I haven't had any problems with snails by carefully soaking in plain water and then looking through the plant while rinsing. It can be a bit time-consuming, but it's worth it to get the snails off. I use the foil pans again as I'm trimming the plants. I put the plants in the pan while I finish up with the water change, and then I trim the plants and put back. With my hygro stem plants, they need to be pulled out of the tank every 3 or so weeks, trimmed, and replanted.
I can't believe how much shipping is for plants! The actual cost may not be that much, but for the value of the plant, it is a lot, like you said. I'm lucky that the hatchery I go to has 4 big tanks of plants!