We've filled an entire growing rack - mainly with sprouts that we plan to eat, but also with some seedlings for this season - a few herbs and flowers that need an extra long start to their growing season. It's a nice ritual each morning, turning on all the lights (or having them come on by timer before we even get out of bed!), unwrapping the heavy plastic sheeting we have around the rack to keep heat in, checking the plants for moisture, having my 3 year old helper fill the spray bottles and mini watering can to give each tray the water they need for the day. And in the evening, happily stoking the wood stove next to the rack to bring a little extra heat to the seedlings.
As our starter soil we use a certified organic grower's mix which is used by the professional organic farmers who we know. It's the Pefferlaw brand, which is widely available in Ontario through various garden centres - here is a list of where you can find the soil. We actually ordered directly from them, and got a skid delivered (45 bags x 85 L soil) and split this with another friend last year. We still have a little soil left as this was a huge order for us!