I start my seeds in 3 ounce white plastic cups, 3-5 seeds per cup. Rarely, I will do 1 or 2 seeds per cup if it is a hard to find seed that I do not have many of.
https://www.walmart.com/ip/Great-Val...Count/12167406
Less than 3.00/100 cups at Walmart. They are cheap, easy to find, easy to cover with a sheet of plastic wrap until germination, and easy to water when necessary. I separate individual seedlings while they are still small, before they go into the Solo Cups