They have expanded their selection since I was there previously. They carry a wide selection of product. However, if you need something generic, check with the big box stores first.
I bought a no-name T fitting for Poly B to Pex for $7.95 at Plumbateria. The identical, name brand part at Home Depot was $1.79. Now I appreciate HD probably gets a better price but 4x better? I asked about shut off valves and they said they ran $24 each. Again HD had very good ones for $6.