its pretty common for small shops to not inventory parts. When your small you can only put so much on the shelfs with the hope its bought.
Its all in how you handle when your supplier is out of stock. Most suppliers will lead the vendor into thinking the product going to be here next week when its 2-3 weeks out. When your dealing with parts coming from over seas, its a guessing game. I have had containers get lost, i have had one get every single part inspected, took 2 months... I even know someone who had small parts with them all boxed into large boxes marked made in china, Since each part was not indiviual marked it would not clear. Luck they guy was a 1 day drive from customs. he had to drive his but there and stick stickers on ever item. All 30k of themso he could get them.