I've been curing olives for quite a few years and have run the range of lye cures, salt box cures and various brines. After a number of variations I find that I'm happiest just using salt and patience. It doesn't get more simple than this but it does take some effort in the beginning and a lot of patience as they cure.
By not using more complicated cures I can wait to decide what to flavor them with and marinate them with herbs, oil and other things like garlic or peppers in small batches to suit whatever mood I'm in at the time. Though most often we simply eat them as they are from the basic brine.
If you don't live near an olive area you can order raw olives online. They range broadly in price.
I arrange ahead with an oil producer who is kind enough to sell me olives from his orchard. I get them for about $2 a pound. In past years even curing 4-6 pounds has left us buying olives by the end of the year. This year I'm putting up about 8 or 10 pounds.
I try to plan ahead as best I can and understand that the olives I put up today will be the ones we are eating the following year. Once you get in the habit it's pretty simple and makes for a nice seasonal family tradition.