I don't know what kind of wood the usual hardware store dowels are made from. If you buy them from a lumber place, they can probably tell you. Also, it's possible to get dowels in any wood, if you know where to look (I did an online search, so I know lots of varieties exist.)
I've purchased two pairs of store bought wooden needles. Both were rougher than my hand sanded needles. I'm sure there are good brands out there, which would be better than these I bought, and as good or even better than my handmade ones, but these were pretty bad. I recommend feeling them before you buy them, if you buy pre-made ones.
Bamboo needles I've bought have been very smooth. Smoother than my own wood ones, because they use some kind of coating to make them slightly more slippery. Of course you could coat your handmade needles with a wax to make them more slippery. I've never done this; I haven't found it necessary. I would probably do this if I were to attempt another pair of long needles. I like the unfinished wood for DPN's, but prefer something more slippery for long needles.
KnittingHelp Queen Bee
"There is a vitality, a life force, an energy, a quickening that is translated through you into action, and because there is only one of you in all of time, this expression is unique. And if you block it, it will never exist through any other medium and it will be lost. The world will not have it. It is not your business to determine how good it is nor how valuable nor how it compares with other expressions. It is your business to keep it yours clearly and directly, to keep the channel open. You do not even have to believe in yourself or your work. You have to keep yourself open and aware to the urges that motivate you. Keep the channel open."
— Martha Graham