This video by LDSPrepper shows just how easy it is to start your own indoor sweet potato slips to transplant into your garden this summer. He does an excellent job showing the kind of results you can get and how to remove the slips for rooting. It might inspire you to plant your own slips instead of getting them mailed to you from a seed supplier or buying them from a nursery.
Basically you just need a couple of sweet potatoes, chorine free water, some jars, and some large bamboo skewers. I imagine using a sweet potato in a submerged net pot would work well too. You simply suspend the potato over the water with it's bottom end dipping into the water filled jar. Next you need to place the jar on a warm surface near a radiator or a heating vent, or you can even use a seed starter heating pad. Sweet potatoes do best in warm temperatures so don't neglect this detail. After a few weeks you will start getting sprouts out the top of the sweet potato. Grow lights can help make these slips stronger and more hearty. As they get big enough (4 to 6 inches long), twist off the new sprout and place it in a separate jar so that it can develop their own roots. When the roots of each slip grow to about an inch long, you can plant them in pots with soil. Keep them growing indoors until it's warm enough outside. The expert advice says to wait 4 weeks after the last frost before planting outside. To get nice large sweet potatoes you need a good four warm months to grow them in with lots of water. The best soil is lower nitrogen and sandy soil.
You can get around 4 to 5 sweet potatoes per slip so plan your garden accordingly. Each potato you place into a jar can produce 12 to 15 slips. That's a pretty good deal.