I got them online here but you could find them [or similar ones] at your local nursery. I like how they are pretty much ready to use - just add water and pull back the netting a bit.
These were started a week or so ago - with the tray on the seeds start to sprout in a couple of days. Also the percentage of success was almost 100%.
As you could see I put WAY too many seeds into this tray. Hey, it was the first tray I used and I was actually expected only like half the seeds to sprout since I was getting less than that when I planted it straight in the ground. Like I said, pretty much 100% of the seeds sprouted :).
So far, I really like these little Jiffy pots. I'll try to transplant a few into the ground soon - stay tuned! Crossing my fingers for a good autumn garden.