The ITC is the independant tournament circuit that uses objective markers in every game. Each player typically needs a 1,2, and 3 numbered objective marker on a 40mm (termie size) base. THere are 4000+ players logged in the itc circuit as of now so that is a decent pool size to pull from. Larger events often use custom markers for their event (LVO, TSHFT) as part of the prize/entry package. Focusing on a 1,2,3 marker set would be a good idea imo, and easy to replicate into a 1-6 setup as well.