For sale is a Linhof Technika IV+ sports finder set, which includes the parallax correcting eyepiece that mounts to the cold shoe on top of the body plus the wire frame which mounts to the top of the front standard. They both fold down, and the wire frame happily stores inside the closed camera even with a lens mounted. See the attached pics from my Technika V (which just sold) to see how they mount. They are in great shape - the eye piece has normal expected wear but everything works great. Cost is $58 shipped in the US by Priority Mail.
$40 shipped, and I'll throw in a Graphic Film Pack adapter which, in your copious spare time, you can painstakingly convert into a holder for wet plates...
Or, instead of the Graphic Film Pack adapter, you can have a 0.35mm pinhole lens permanently mounted in a Linhof Technika board. See photo...it is a lenscap pinhole lens that has been installed for 4x5 use, with F-stops labelled for the various useful focal lengths...