Lucky Mojo and a few other author sites seem them, my local coop food stores sell oils and bulk herbs and spices.
Particularly candles though, do 4" candles burn for quite some time? Those and votives seem to be the best deals through amazon.
I admit, I never really had any more utility from using a manufactured, purchased candle over, say, a visualization.
The only time I ever got any more effect was when I forced myself to make my own.
Buy a block of beeswax, heat it until it is "soft", and then split it into long, flat half-square-by-end-profile segments.
Heat one side of two such blocks till they are 'juicy', and press a wick between them before the wax hardens. Give it a good press so wax squeezes out from both edges of the interface and then with the warm knife, carve the corners off, round it up, and then smush the trimmings back into a block for future candle making.
Such candles will burn for a VERY long time.
If you wish to make your own wicks, go out into your yard (if you have one, also, weather permitting) and locate a sapling no taller than about 2-3 feet or so.
Uproot the whole thing.
The root should have a long wiggly, flexible sheath around the harder woodier core. This is what you want.
Pound the whole root a few times between a mallet and anvil of any kind to free the root pulp.
Set aside the stripped root core and adjoining sapling for later use as a cat toy (if you have cats).
Take the root pulp and using a sharp knife, strip the outer layer off the white inner layer of the pulp.
Throw this (usually yellow) skin away.
Smash the pulp to soften it and then slice it into long, thin strips, and then wash these in alcohol, and then water to remove any bothersome residual stuff.
Weave these strips together and you will have an effective wood wick, generally long enough for a 4 inch candle per root.
