It does seem any Oliver travel trailers up for resale do not stay on the market very long.
When I began looking for a true four season trailer capable of dry camping
for many days in the northern New England climate, there were only two manufacturers producing that kind of product, Oliver and Earth Roamer. All you need to do is look at the price for an Earth Roamer and you see there is only one available price-wise.
Since Oliver currently appears to have a specific niche market all to itself and the trailers are built to last, I can not imagine many will come up for resale on the open market. Like Earth Roamers they may go through the resale process via word-of-mouth facilitated by the factory in Tennessee.