You can get fresh ones. Well sort of, the preparation post-harvest involves a leaching process using caustic soda IIRC to leach out bitterness. Not sure for green olives but definitely for black.
Right now I have a baby to look after and I can't just waltz off to the shops while she's busily evaporating the solvent off her. Or she'd scream and cry, if overheated. And so would I. Because unlike one the result of sticking my dick in a female human or female NT, I can't readily replace this. Well I can but whilst there is no quantitative limit as such on the egg to be fertilized, there is a time limit on quantity over given time. And THIS baby is special, special enough that I'd not even apply ammonia, benzene/toluene or ether and add hydrochloric acid in ethanol, even carefully. This, has to have the water gently and lovingly stripped off before being dissolved in anhydrous acetone, put in the freezer and then an acid halide or acid anhydride added dropwise as a solution in anhydrous acetone, with NaHCO3, a nice gentle base for the gestating wee nipper to suck up the hydrochloric acid (have tried the buyryl diester using the acid anhydride and r eall, rathwr a waste og baby.