The good folks at Disctek Media are bringing all 78 english language episodes in one volume. This includes the extras from the DVD version as well as the original pitch video where the world of Sonic X had a lot less humans. It is releasing on May 28th and up for preorder at quite a discount. Keep in mind this isn't in HD, it's SD video on Blu-Ray and hasn't been remastered. This is the first time I've seen this as usually SD discs are put on DVD but the added benefit of these being on Blu-Ray is less discs are needed due to the larger file size.
The Blu-Ray retails for $69.99, but you can pre-order it from rightstufanime right now for $45.47. In case you have forgotten or not aware, jump on this deal while you can!