buy your seeds from the internet. best by far is mountain valley seeds out of utah. great prices and quality.
sell on e-bay or whereever.
example beet seeds: sell for 2.50 a ounce---your cost around 5.00 a pound for detroit red.
better than some people selling a pack for 1.00(5 grams or less)
use your imagination, search,compare!!
remember to follow most state laws by listing germination rate,year produced and lot #. mark

Collect your own.
(Of course it's kinda late now to sell them for this season, as you've missed the harvest time)
But for next season,...

I always harvest my own garden's seeds (More profit for ME) print out some nice seed templates with pretty pictures, fill them, seal them and
arrange them in a vintage wicker basket on a market table for 2.00 a pack.

They FLY in the Fall!

ALL profit except the paper & ink for the seed packets, (Oh yeah, and your time)

You can easily harvest your own herb seeds,
and as long as you don't grow hybrid veggies, could even harvest their seeds.

Even if you only did it that way the FIRST year to see if they'd move, without wasting any of your own $$ buying bulk and maybe have it sit.

At any rate,..Whever you get your seeds, don't forget about the PACKAGING. Make your seed packages pretty!