Stefan being in a high humidity environment has to deal with wood differently than a lot of us.
If the wood is stored indoors where an air conditioner is running it will continue to dry or stay dry. The A/C works as a dehumidifier. Otherwise it will level out at about 16% moisture content.
Marko has made one of the most important comments in this whole thread.
Allow untreated wood time to settle, even if bought locally.
Kiln dried woods are usually dried to about 6 or 8%. After that they are usually stored in unheated warehouses so the moisture content fluctuates with the weather.
The biggest thing you can do to protect wood is to seal it with a good finish. Epoxy covering the unseen areas against the tang and inside pin holes, plus a good finish on the exterior. Then maintain the exterior with occasional oiling or wax. (Think of it like a good pair of leather shoes. If you don't take care of them and polish them once in a while they will deteriorate over time.)
The olive on a lot of the commercially made knives is old growth olive from overseas. A lot different than the orchard grown olive from California. The orchard grown woods tend to be a lot less stable than ones grown in the wild. I am (guessing) pretty sure it has to do with rate of growth. Same thing with orchard grown walnut. Takes longer to dry and moves more while drying.
You can find some good wood on ebay.
But you have to be selective and be willing to gamble. There are a lot of people who see certain woods selling for a lot of money and think "We have that here, I am going to sell some". They do not always know how to cut, dry and care for the wood.
I have bought wood on ebay with mixed success. Usually my first purchase from a seller will be a small purchase so I can evaluate the wood and the seller. From that I decide whether to go further with that seller. Best rule of thumb to use when buying anywhere; if the price is really low, there is probably a good reason.
A side note about do it yourself stabilizers and ebay sellers.
There are some good ones. Example: Craig Stevens.
He is friendly to talk to, does a good job stabilizing and knows how to cut the wood correctly.
He starts the bidding at a reasonable price. If the bidding goes to an excessive price that is because someone is willing to pay all the money to get the piece.
Mark, I'm not sure that the olive wood from Europe is "wild" but suffice to say that they have been growing those trees for thousands of years over there and the wood probably comes from old, funky trees that are no longer producing sufficient olives for the oil trade. I suspect that you are right about the growth rate because the climate is probably a bit drier on the Med than in California and I doubt that they irrigate the trees over there.
Thanks again, good info here. Just to make sure: I have bought tons of great wood on ebay, but after a while you know some reliable sellers and come back to those more often. What I had wanted to say was that I would not buy stabilized wood from just anybody. The two DIYers that are excellent are Craig and one other guy who's name I forgot (but I haven't seen him in a while anyway). Others explixcitly state that they ae using WSSI or K&G.
Now, the first big decision of the day. To get up or to turn around one more time, I was reading and browsing way too long last night. The dangers of reading books on an Ipad.
A little over a year ago I bought a big gunny sack full of clarinet rejects.
Some of the wood was black, some dark brown. I was surprised to see a metallic flash in a lot of the pieces that would reflect different colors. Metallic green, bronze and purples. There were even a couple pieces with 2 to 3 inch areas of burl. The clarinet makers were rejecting anything other than straight grain flat black pieces. I think this is one of those cases of "One man's trash being another man's treasure"