Here is where I got the parts for the 2010 suspension upgrade. Their prices are about 20-25% below local dealer quotes. You pay shipping, but no state taxes. This is a real Hyundai dealer in South Carolina.
http://www.newhyundaiparts.com/
I doubt they will give you much of a break for a group buy, especially if they have to ship to different locations, or if they all go to a single member in the group, that person will have to re-ship the items (which gets expensive). Probably not worth the trouble to even try and organize it.
Hardest part is probably going to be to find a qualified installer to do it at a reasonable price. I paid about $625 for my 2010 upgrade install (labor only) at an independent suspension shop (plus $1025 for parts from above website). Dealer will probably want about $1500 - $2,000 just for labor (this assumes 4 springs, 4 shocks/struts, and rear stabilizer).