I'm making ogam tiles now from locally sourced storm-felled or pruned branches. Here's one of my most recent sets:
Description: Silver maple, 25 tiles plus 1 replacement blank, made from a single locally sourced storm-felled branch using traditional hand tools (except for the electric wood burner used to incise the characters). Each tile is approximately 1" long, and has an ogam on one side and its name in Latin characters on the reverse.
Available woods at the moment: silver maple, red maple, apple, honey locust, ash, elm, rowan. Sets currently sell for $25 (not including shipping).