I saw something really pretty several years ago in Kechi KS (near Wichita). They used railroad ties, cut them different lengths and stood them on their ends. Kind of labor intensive but would last forever.

careful of the rr ties, especially the old rr ties as they are coated in creosoote, which can leech quite a distance, apparently.

have you tried freecycle? Also, do a search for re-claimed brick. This is really old brick from buildings being knocked down. Rather than put in the landfill, you can re-use them in your yard, for a price of course.