If you are NEW to pack film, this is an overview of what to look for on Ebay. I did forget to mention that the 100 (and other models I referenced) have a light/darken adjustment. ALSO, the 250 does not have the "automatic timer" as mentioned...but the 350 most certainly does. The various models do get confusing...so here is a reference list: http://www.landlist.ch/landlist/landdcam-pack.htm
Also, in regard to the Flashgun #268 I forgot to mention it too has a battery compartment that you want to make sure isn't corroded ... it is a simple AA battery, but important it is clean to actually work.
Kickstarter for Pack Film: https://www.kickstarter.com/projects/1755997589/one-instant-analog-packfilm-re-invented