I was at Hilo Farmers market Tues & Oscar's pricing was right on the money. A lot of vendors had lychee and the going price for Kaimana was $3 / lb. I did see another variety there going for $2.50. A year ago, 5 or even 6 papaya for a dollar was not uncommon at the HFM. However, now something like 3/$1 is more typical. If you check supermarkets on either side of the island, prices are typically crazy and the fruit is often not local.
I have tried the farmers market in Kona a few times and I have never caught Ken there, it seems he is always travelling when I visit that side of the island. The stuff the other vendors brought there seemed less "exotic" than typically seen in Hilo.
I think we have some microclimates where seasons vary a bit. For example, you may have a situation where something has finished in Puna but is still bearing (or has just started) along Hamakua (or vice-versa). Hilo market generally has fruit coming in from both these areas so the item may be present at Hilo market longer than it might be at Makuu, for instance.
John