$650-$1200 seems to be the range for the various firewire or cardbus options (some exceptions either way). The category is fairly new, and now you add usb 2.0 (I am not aware of any audio i/o cards with this yet), and you see this as an emerging areas.
Your needs/software will vary the decision. The choices I am (have) considering(ed) are:
All in one systems
-- In general have nixed these b/c you usually lose out on some features, like # of i/o, midi, quality of components, and the inability to insert a compressor or brick wall limiter between pre and i/o
--Echo Mona - was strongly looking at Mona until midi and compressor became a need for me -- also, only 4 in's w/ no expandability. Pre's are supposedly good, though not great on DI guitar
--Motu 828 or 896: 828 is not 96k, no midi, supposedly not great pc or customer support. 896 - expensive, big, supposedly many of the same 828 components, which aren't the greatest
--
Focusrite OctoPre -- this is interesting, has compressor on each track, 8 pres, can do 96k through adat expansion board. Really seems like an add on, not replacement for an i/o card.
--
Presonus Firestation -- very interesting, not sure when it will be out, firewire (mlan) based
--Metric Halo mobile i/o - looks very cool, BUT no PC support today - site says coming soon, when emailed, response was "I don't know, maybe a few months" - not encouraging. Also, upper end of price range, if not beyond
--Crest audio - don't have alot of info but pricey
Strictly i/o
--Echo Audio: Layla still under serious consideration
--RME HDSP: Was on a waiting list 8 months ago for it, but then gave up. If available will likely be a strong contender. Small, lots of i/o, expandable, 96k adat, midi, some dsp for low latency monitoring. I use Sonar so no WDM initially crossed it off the list, but recent review shows very favorable latency (see cakewalknet.com).
None are pefect for me but it is probably down to the layla for HDSP. Ideally this is what I would want:
--Firewire or usb 2.0 based - no need to buy/install separate pci and pcmcia
--6-8 i/o's, though expandable (linking multiple units)
--96k adat
--2 defeatable on-board preamps with brick wall limiter (for simple stereo all in one recording - not needing additional pre's/comp)
--midi
--metering and headphone on breakout box
--1/2 to 1 rack space
--software upgradable
--giga and wdm support
--ability to run w/o being plugged in, or at least alternative portable options (battery, car lighter etc.)
jeez, now I am getting myself thinking that this really exists. A guy can dream I guess.
