My visits to my closest Lego store are rather infrequent (1x/quarter?), which is not helpful in reminding me to take a PAB cup with me. When in the store, I then didn't get a new cup as I thought it was silly to pay EUR 0.75 again.
Realising this was probably rather silly of me, I calculated the value of this weekend's PAB cup. (For once I didn't forget!) Looks like ordering these parts from PAB online would have set me back EUR 68. Only EUR 25 from BL, but having to pay for P&P from multiple sellers would have eaten into those savings.
So lesson learnt for me: don't forget the PAB cup. If I do forget it, just pay the EUR 0.75 for a new one.