Does the school have a greenhouse? I could visualize various outcomes from this venture, some good, some not so good.
By involving the students you can cut labor if the students are adequately trained on transplanting and daily care. I would give minimum consideration to the containers; commercial plastic pots are pennies each.
Your biggest considerations for such an event are light, heat and water. Without those three components well planned you may be risking a waste of time.

Raising money for teacher expenses is a great idea.
I think this is risky though. Damping off. Bugs. Too much, too little water.
Could you maybe see if you could get volume deals for some stuff and sell an heirloom 'kit' complete with potting mix, containers, seed, and instructions?

I am a teacher and we did this for an activity I got a small grant for. We grew about 100-150 plants, tomatoes and peppers. If you have never grown plants from seed, I would start now small. There is a learning curve. I wouldn't try the first time be when you start 2,000. I am a market gardener and have grown my own transplants for over 10 years now.

First of all, you would need to start them in small flats, 98's to a 1020 tray would be a good size then pot them up into either 2401's or 3601's trays that you could break apart to sell.

Greenhouse Megastore is just one source for these trays. I would suspect you would want to grow single plants and not 4 packs. As most people will plant 4 tomatoes, but they want them to be 4 different tomatoes.

You can grow these plants to sellable size under flourescent shop lights. Just make sure you use 2 four foot lights for every 4 trays.

I would grow a variety of shapes and colors.

Jay