Is there a place I can look specifically to find these? Can I plant them via seed and have them ready by summer?

They are hard to grow from seed but sometimes some of us manage. The seed needs to be fresh and planted in the fall in the ground for best results.

If there are Asclepias (milkweed) growing wild in your area, watch the plants and collect seed as the seedpods burst.

My local nursery always sells the more colorful Asclepias as 1 gallon plants in the summer time. There are also some online nurseries where they are available as plants.

What type of milkweed do you want to grow? The "common milkweed, Asclepias syriaca ( Common Milkweed (Asclepias syriaca) ) grows all over where I am (near Escanaba in the Mich. UP), but there are a number of other types, such as "butterfly weed," ( Butterfly Milkweed (Asclepias tuberosa) ) which is commonly sold in seed catalogs and garden centers.

If you plant common milkweed, be warned that it will really take advantage of cultivated soil -- which may or may not be a good thing, depending on your goals!

I have seen packets of seeds sold in nurseries. And I have seeds that I 'captured' but haven't planted yet. I recently gave in to temptation and bought some gallon-size plants. But as @Weedwhacker asked, 'What kind do you want to grow?'

From what I've read, it's best to find out which kinds are best for where you live. There are several sites that will only sell seeds that are appropriate for your area. Just type 'milkweed' in your search bar and you'll find a lot of sites and information.