Gundam Seed on Ebay

I was looking on Ebay for Gundam Seed DVDs, I am looking for English dubbed by the way. Anyway, I know that it is possilbe to buy low price box sets on Ebay. I have bought Gundam Wing, Escaflowne, and Berserk this way. My question is, does anyone know when these specific box sets are relesed? Does it depend on when the offical DVD are released or not?

Thanks for any info