There are several coil-over kits that are coming out in 2005. KW Suspenions will have their kits due out in January priced at around $1200-$1800. The Mazdaspeed coilover kit should be out at about the same time (it is being built by KW apparently). D2 already has their kit available for about $900. Tein has their Mazda3 kit in development. Hopefully the Tein kit SS kit will be out by March 2005. No word from JIC Magic, HKS, or Bilstein.
I've emailed the respective companies mentioned about the Mazda3 and JIC, HKS, and Bilstein seem to be completely ignorant of the existence of the Mazda3 (figures since the apparently only Honda, Nissan, Volkswagon, Audi, and BMW make sporty sedans worthy of their products). I'm surprised that Tein has been taking their sweet friggin' time to make products for our vehicle (They already made suspension products for the Scion tC, which came out after the Mazda3). They already have coil-overs for the Mazda6, so I figured development would be pretty quick since the 3 and 6 share suspension components (at least in the rear). KW has been kind of slow but they make an awesome product and they've been doing a lot of work for the corporate skunk-works such as Mopar and Mazdaspeed. I haven't heard much about D2 (fairly new company I guess...) but the thats one hell of a deal when it comes to coil-overs ($900 and they have adjustable dampening!).
Hope this helps....