I bought some taro corms from the stand about the middle of the downtown side of the Kinoole Saturday farmers market last year and they grew fine. The market will be open this Saturday, although I do not know if this vendor will be there.
In the CTAHR book "Taro Mauka to Makai" it says you can also divide the corms into pieces (1x1x1 inch) with an 'eye', like Irish potatoes, to make faster increase. Put the cut pieces in a "freely draining commercial planting medium" like vermiculite in a flat, completely cover with medium and place in a partially sunny area and keep moist but not soaked. It does not say anything about letting the cut pieces callus before planting in the flat. That would be a lot cheaper, but slower, than buying huli or potted plants. The Pahoa Feed store has had Ele Ele (do not specify which one of several) plants for $1.50.
I like the araimo = dasheen and planted some corms from the farmers markets about a month ago and they are just starting to come up. I am in HPP on 22nd.