I bought the cheapest one (2-steps) from my local TSC for me and my neighbor to use. So far so good for several years. My trainer has 3-steps one, but I always feel that it may trip over when I use the 3rd step.
I also bough light step-up in HomeDepot (for $10 or so) I keep in my trailer if I need it to get on when I go on trails or to the lesson. It's not as reliable and sturdy but still does it job (and very easy to move unlike mt block).