I believe there are many cards in many price ranges, depending on the features you need.
Questionlist:
1.Do you need low latency? ultra-low?
2.Do you need multiple i/o? how many? balanced audio?
3.Do you need digital i/o?
4.Do you need on-board dsp?
5.What applications do you use (unfortunately this is of some importance still)
6.What os do you use/plan to use?
7.need mic amps and internal mixing/monitoring?
The price will depend on all of the above factors. Those saying that "you need this $1000 card as its the only professional out there" typiclly don`t know what they are talking about. There are typical "pro" cards out there that costs little more than a sblive, but they may have very few features (only digital i/o for instance).
Answer the above questions, and I will try to give you some advice.
Some brands to investigate:
*Creamware. Very powerful dsp. somewhat high price for a given number of outputs. expandable and low latency
*m-audio/midiman. big range of pure i/o boards (no dsp). not very expandable but good prices and driver support
*yamaha dsp factory. slightly dated but contains all of the dsp from one of their multi 1000 dollar digital mixers. Expandable, but offers few i/o out of the box.
Knut