I order maca from macaweb.com. I get one kilogram (2.2 pounds) of the plain raw powder. The current price for that, including shipping, is about $36. That lasts a long time. They also have smaller sizes of raw powder, and capsules.
It comes in a big foil-lined ziplock bag, so you would need some kind of small tupperware kind of container for daily use.
I take one teaspoon a day in a little fruit juice in the morning, which I think is a typical dose.
I think it’s best to take it early in the day. It can give you sleep problems if taken late. It seems to be helpful to me with my overall energy level. I haven’t seen any consistent erectile effect, but I think it helps with ejaculate volume. Of course, as with all this kind of stuff, YMMV.
They also sell something called gelatinized maca, which however is still a powder. I’ve never seen a straight story on what it is or why it should be better than raw powder.
I think it’s worth a try. You could start with a pound instead of a kilo, and try different doses, and see what you think.