Spill planes are unique in that the “shavings” are the product. Since spills went out of general fashion about a hundred and fifty years ago original spill planes tend to be hard to come by and expensive. There are few on EBay right now but it can be difficult to separate originals from reproductions. I would recommend that you keep it on your future project list until you feel more confident in your skill levels unless one of the forum members feels extraordinarily generous.
Lee Valley has a version of one available for about $50 and there are numerous videos on line on the subject.