Love cacti. Such a forgiving and fun plant to grow/watch grow
...I would look into ordering cuttings online as nurseries aren't always the best in regards to what you're looking for. Most nurseries sell the san pedro "PC"cultivar that is hit or miss and if it is active, pretty weak. Look into Misplant/sacred succulents/mallachts plants for good cuttings with good genetics. Even ebay has some good ones....Look into trichocereus bridgesii and trichocereus peruvianus as well. There are so many different trichocereus hybrids out now as well that vary in the goods. Collecting em gets addicting lol.
Growing from a cutting is much easier and faster as all you have to do is stick the cutting in the soil and wait for it to root (about a month or two) compared to sowing seeds which is easier to 'mess up' and it takes about 2 years to start to really grow - a cutting can grow 6" to a foot a season.
Lophophora Williamsii is a different plant altogether. you need patience...... a lot of patience
but definitely a much more special plant.