The real cost ist hidden in the details: "Programming packs" for certain chip series starting from $1500 and socket adapters from $300 each.
Programming
Paks were only used on the 19A & B, and 29A & B programmers. When the Unisite40 was released in 1986, its only accessories were the pin driver boards, the Site40 DIP module, the SetSite gang module, and the ChipSite module that supported a range of PLCCs using separate sockets. The PinSite module came later, with the updated UniSite that supported the internal hard disk. Using the PinSite, you could use a range of carriers including the PLCC, QFP, LCC bases with the conductive film, or the PPI base that took socket modules. None of those were in a 1988 price list.