I have 8 molds, 5 of which I got second hand and for an incredible deal, all in all I have about $200 invested but I've made all kinds of terrain elements: bridges, ruins, buildings, low walls, shrines, tombs, so I think it was worth the investment. New molds orederd from Hirst Arts range from $21 to $34 US with smaller simple molds like floor tiles or roof peices at 21$ ranging up to the more intricate dungeon pieces at the $34 price. As Coil said if you get into this you're going to want to use a more resilient plaster like dental plaster, hydrostone, or hydrocal, since regular plaster of paris doesn't have a lot of strength and is prone to chipping. And yes if you want to do something like this I would recommend picking up the dungeon accessories molds, future installments in my SotC boards will involve more senic elements like columns, scones, niches, skulls, teeth, but when I got the idea all the blocks I had cast and ready were basic blocks so I had to cast the fancy ones, so they weren't ready for this part of the project. The boards are mounted on 1/8th inch MDF, a lot of people mount thier Hirst Arts dungeons on 1/2" extruded polystyrene but I feel that makes the pieces too bulky and doesn't really have any advantages over the MDF.
