Don't know what the timing of your plans are, but AC Moore and Michael's have them for $3.99 or $4.99 on Black Friday - at least for the last three years.
Another option we used for one of my son's class activities - second grade, was to make a winter scene using graham crackers instead of gingerbread pieces. It's the same idea, just a bit smaller. Then the kids made whole yards, some with ponds and fences and walkways. It was a lot of fun and certainly not all that expensive.