Try Target -- the Assets by Sarah Blakely line. It's Spanx for the lower-end stores.

I have a basic black pair from Old Navy.

Are Assets pantyhose? I haven't quite figured out if leggings are pants or hosiery.

Will take a look at old navy.

Ha, I guess I think of them as somewhere in between. You wouldn't wear a pair of pantyhose/nylons/whatever your word for them with just a long tunic, but you might a pair of good leggings. I don't have any long tunics or anything so I tend to wear mine under shorter dresses or skirts.

I was at H&M the other day and one of the employees was sporting a pair that they carry right now that look like denim. She had on a long tunic (belted I think) and the leggings were tucked into spring-y boots. I liked the look. They may have had other colors there, too. I can't seem to figure out their sizing, though...I was swimming in some things or sausaged in others (I'm a 16). Trial and error, there!

If you find a good pair, let me know!

The Assets line has leggings, hose, and Spanx. I was surprised they had it all!

I have had very good luck with the plus size of Spanx leggings. Have both the ones that go to mid calf as well as ones that go to my ankle that a bit heavier for colder weather.