I've bought quite a few inexpensive bamboo needles on ebay the last few years. Quite the bargain, and seeing as I'm a hoarder I like to have at least 3 sets of circular needles in each size, and double pointed needles as well.
The only problem with these needles is that they're rather rough and don't seem to have been properly finished. The can still be used as they are, but they will snag the yarn a little, and it will be hard to move the stitches up the needle. After having scoured the web for solutions to this I've come up with a solution that works for me.
To make your needles nice and smooth you'll need the following:
A nail buffer
Fine grain steel wool
Some lint free soft cloths you're prepared to throw out afterwards
Furniture oil, I use MP 52 møbelolje, which is meant to be used on untreated wood. It hardens the surface as it dries, and makes the needles very smooth.
If your skin is easily irritated I'd also recommend wearing latex gloves.
The first thing I do is to smooth the points of the needles with a nail buffer. I use the side that's meant for smoothing ridges from fingernails. Watching a film while doing this helps, as it's rather a monotonous chore. Once the tips are nice and smooth I use a fine grade steel wool to smooth the shaft.
Wipe off the dust with a soft cloth, and use a fresh cloth to oil the needles. Follow the instructions on your furniture oil bottle. If you are using the same kind of oil that I use the cloth you use to oil the needles will have to be thrown out. The oil gets stiff as it dries, and won't come off in wash.
When I've oiled my needles I polish them with another cloth, and leave them to dry overnight on a paper towel, the next day I polish them and then oil them for a second time. Once the oil has dried, and I've polished the needles they're silky smooth. Not quite as smooth as new wooden needles of good quality, but near enough :)