Does a portable ILS ground station exist?
NASA did some research on it in 1986 and published this paper. Thales was contracted to build one that the US Army has ordered and it made it to prototype phase. Eventually it was tested for a while and appears to have made it to production and the military ordered more. 

It goes under the name Deployable – Instrument Landing Systems  (D-ILS). here is a short two page brochure on the unit which has some good pictures of the whole thing. 

It looks like the units cost around $4.68 million each.