In my experience, milkweed isn't carried by those big-box stores.
I found mine at MRT in West Bradenton.
You may have better luck finding it at a larger nursery, but be warned...it may have been previously sprayed with pesticides!
If so...the cats should not be allowed to ingest any of the plant for at least 8 weeks, I believe.
Someone correct me on that time frame, if I'm wrong, please.
Meanwhile, you need to flush and flush and flush the soil...and keep the cats off it. :)

I did a quick Google search for nurseries local to your area. Maybe one of these will have some milkweed....

Pasco County Nurseries
Google Nursery Listings

Be careful about getting milkweed from the big box stores. Usually they are loaded up with pesticides and unfit for monarch consumption for several weeks. Try the local nurseries, but I would call first before wasting a trip.

Do you mean asclepsis curassavica? I have some seeds I can send you.

I never thought about sending seeds!
I have many!
Actually, I thought you needed plants NOW for your babies, but if you need seeds, email me, aqua, please.

Sorry for not getting back to everyone sooner, my pc crashed :( I was able to find some in someones yard and they were reall nice and understanding when I knocked on their door and explained my situation (I felt like a real wacko and prayed they wouldn't call the police haha). I got enough to feed my guys until they went into their chrysalis. I have seeds that I have now planted and hopefully will be rewarded with lots of plants. Again thanks for everyones quick responses!! I was really worried about them because they went almost 24 hours without food. I felt like a terrible butterfly mom lol.

While not in Pasco County, Kerby's Nursery in Seffner (off I-75) usually has a good stock of butterfly plants.

Here is a link that might be useful: Kerby's

I can relate to the desperation you felt in trying to save your babies. Two weeks ago, I was in the same position. Went out with DH and made the rounds until I found a nursery with nice large plants. I bought 6 3-gallon ones to get my baby cats through the crisis. Well, I should have checked the plants closer....the were covered in eggs. I made it through the first crisis but created another even larger one. At this point I have a wonderful collection of "stick plants" and plan on letting them re-leaf naturally and let nature take its course. I went through this back in February and swore I wouldn't make myself crazy again.....but this time I really mean it!!!