There is one other way to get them and it works very well for me. I actually only get around 6 each day but some days I can get up to 12 or I can get only 2 in an hour of work. It's choco digging but you have to be level A10 to really have a chance at getting alot of them.
The down side is you can only dig up 100 items in a day unless you have gear that enhances your digging which takes me about 35 minutes to dig up 100 items before work each day. It's slow but it's enough for me to make dippers for myself and sometimes have enough left over for selling.