Marklin came up with the idea to release Halloween themed cars as part of two starter sets beginning in 2003; they included track, loco and set 00832 included a couple of ceramic jack-o-lanterns.
Unfortunately the starter sets included the standard class 89 steam locomotive that usually goes in starter sets, but the locos came in black; they would have been better if painted with Halloween theme?
The four cars total for Halloween included 2 per set released 2003 + 2004 respectively. Set 00815 included two cars (type 8600 and 8615) painted with glow-in-the-dark pigment.
And set 00832 also included car types 8600 and 8615 (2 cars total in set) with bright orange and black paint scheme.
After writing this post I realized there are any number of interesting Halloween themed trains including haunted houses, dead trees, candy corn loads for custom painted in orange gondola and on and on. A fun project to break up the long term goals of more serious layouts: we all need more projects?
Siding: collectors tend to sell these cars in pairs so keep an eye out, value for Halloween cars range from $25-$50 a piece; they are the most valuable part of the starter sets and the locos are not special so I recommend going for the cars only and saving some dough.