To give you an idea of how expensive a valk helm alone costs, this is the ingredients + zeny required to make it after you pass the sqi arena
1 Angel Helm
1 Angel Wing
1 Angel Wing Ears [1]
1 Spikey Band
1 Mistress Crown
1 Bone Helm
1 Queen's Hair Ornament
130,000,000 Zeny
(taken from
Here thanks to Warr)
As you might be able to tell, it can be a bit of an expensive process to make, + a card that's worth 17 in ads, adds up to quite a bit. The price is roughly going to be somewhere in the range of 150+, 150 probably being the lower end of the scale, and highly unlikely to find.
Depending on how you want to play in the future, I would advise you use your whitesmith to simply continue to get zeny from nif and buy the helm seperately, and keep your kahos, they're very handy for other classes that you may want in the future. You may find yourself being very sad you ever sold them if you do. Snipers are not exactly money making machines IIRC.