If you need more than the inexpensive vacuum formed lightweight sleds, the best sleds are the ones you can make quite easily from 1/4" Polyethylene sheet. Normally you can buy 8 and 10 foot lengths so get what you want in whatever width you want - up to 4 (standard) and sometimes 5 feet. 32" is usually more tha wide enough and narrower is often better. You can either roll the edges up to create sides or attach them separately. If you need runners to take some of the abuse of the trail, you can attach 1/2" UHMW to the bottom in strips. The sled material can be ordinary HDPE for fairly light use or UHMW for really tough use. Make sure you store plastic sleds out of the sun after the season especially if it isn't treated to resist UV.