Pretty sure Atlas won't be making dcs components like TIUs and remotes. MTH has spun off the DCS group into its own organization to continue the production of DCS components. Atlas will be a reseller and licensed oem provider of these parts.
As for the eBay prices, that's all supply and demand. If you want a better price there are other more obscure sources that require some searching to find. I bought an unused TIU and remote set with an AIU last month for $375.... Not on eBay. While this price is rare and a real gem to find, they are out there.
eBay is the last place to look for a good deal on this stuff.
