i found a easton EA70 stem ($100 msrp) and a race face prodigy ($41.00) for $34 and $28, respectively. looking at the specs.. the race face is only 4 grams heavier, has a shorter stack height and are available in pretty much the same rise/length. what's the main difference? im trying to figure out why the easton is valued at over double the price. im looking into a new stem for XC, which would you recommend and why?

Tough call. I like both Easton and RaceFace. However, I would probably have to cast my vote for the RaceFace stem as that's what I use on my MTB (RaceFace SYStem). This isn't to say that the Easton stem isn't any good but as long as you can find the right size, I don't see the Easton stem offering any improvement over the RaceFace. BTW, are we talking about the Easton forged or welded EA70? The RaceFace Prodigy is forged and thus is probably more durable than a welded stem. Also the Prodigy has the steerer pinchbolts placed in a less damaging (to the rider) position.

the price, and their (easton's) profit margin

You might want to actually check the weights of those for yourself...manufacturers are notorious for inaccurate specifications when it comes to weight. The 2003 model Race Face Prodigy stem was 232g for the 110mm version. The Easton EA50 (a step BELOW the EA70) is 179g for 100mm version. One would assume that the EA70 is even lighter. I know that for 2004, the EA70 forged is 160g, that's the real weight for 110mm version.

i have a prodigy in 80mm length and that thing is awesome.i do not know the weight(or care) but it is the right angle,right height,was the right price,right warranty,just to name some of why i got it plus the people here recomended it.