Fullmetal: Just buy a wig that starts out like that? ^.~ Cosworx.com sells the "Punky", "Punky S" and "Punky XXL" wigs. Of these, I've used the first two. In fact, the wig in my avatar is a slightly styled Punky with the back hacked off.
In addition, you CAN in fact use a blow dryer on wigs. Just try to keep the heat fairly low and keep it moving. if you focuse on one area for more than a second or two, you can melt it.
Industrial hot air guns tend to be a *bit* too hot ^.^;;;;;;;;
Kari: For the sake of a cosplay, get a wig. That way, if you ever want to do the cosplay again, the wig's ready to go, no dye-jobs or anything necessary. Looking at it, wigs tend to be a bit cheaper, quite honestly.
Extension wise, you're probably looking at about $10-20 for the extensions. If you get them done in a salon, $60+ is a good guess. (As compared to $25-45 for a good, thick wig)
If you need any help with wig choice or styling tips (I can get my hair pretty darn close to that) just drop me a line, I'd be glad to help ^__________^ As a note, cheap hairspray and a blowdryer is all you need for a good spiky ponytail.
Mastergods: Unless you can put out Cloud Strife wigs in your sleep, I'd suggest starting with the Punky wig (as mentioned above). It's extremely fiber dense, the fibers are already sticking up (and therefore easy to put into those big spikes), and it takes to hairspray very nicely. Just chop off the back, section out the hair for the chunks, shape the spikes with your hands, and hairspray/blowdry.
~Ari-chan
