Quick rule of thumb for soulstones and WR's.
Armor - HP stones.
Weapon - Either Accuracy stones or Attack stones. Either work well, and it depends on which you'd rather increase. Optimally, have at least 2 sockets in your weapon and put one of each.
To make the stones yourself:
G7's cost around 950k gold. This level will get you the glowing rings around your arms.
G8's around 4.6M gold. Usually the stone of preference, since the next level is cost prohibitive if you need lots of stones.
G9's around 24M gold. However, there are lots of stalls around selling these from 5M-18M due to drops from world bosses. Easier to buy from them than to make yourself.
G10+ - PM me, I want to be your new friend...