I haven't seen a really, really plane jane version, but the most basic model seems to be Elmax, MagnaCut, M390, or Vanax (haven't seen this change the price, seems to just be done in runs or based on availability of steel maybe), with varying handle milling patterns and anodizing for $750. The lottery I won was Elmax with plain ti and speed holes, which is about as basic as they seem to get.
The XL is a bit more. Timascus small parts seems to be the only upcharge. You also get dinged $25 for shipping, so it ends up being $775 if you get drawn in the lotto and it was a pretty basic model. They seem to have about 100 knives usually split between XL and standard Rosie in two to four different configurations, open for lotto entries on Friday or Saturday, and draw on Sunday. You have to pay shortly after you get the invoice, and the invoices go out over about an hour on Sunday night. You can enter the lotto separately for any of the models that interest you, but only one lotto entry per knife variation.
EDIT: The skeletonized one seems to be weirdly super popular and I think is also more expensive, understandably due to the loads of extra machine time.