New to horticulture and starting to appreciate all the different varieties of Cactus and Succulents out there.

We are looking to plant some Mexican Fence post up against a south facing wall here in Phoenix (9B) we've heard some varying info regarding growth rates. We've heard slow to moderate. Nursery say slow to justify the cost of larger plants but we have neighbors who said a foot/ year.

Just wondering what some of you all's experiences have been. Wanting to do some mental math to see if paying for larger specimens is justified.