I just tried trading an equalizer to Dispenser 24 for an 'Any Weapon' trade, and this is the log of the encounter (sans security code):
Dispenser 24: This is a PURCHASE session, click READY when you finished adding Any Weapon (Total: 1). 00:51:01
You added The Equalizer 00:51:15
You are ready 00:51:18
Dispenser 24: Please offer EXACTLY the following items: Any Weapon (Total: 1), then click READY. 00:51:22
You are not ready 00:51:30
You are ready 00:51:31
You removed The Equalizer 00:51:54
You added The Equalizer 00:51:56
You are ready 00:51:58
Dispenser 24: Your session has 59 seconds left. 00:51:58
Dispenser 24: Please offer EXACTLY the following items: Any Weapon (Total: 1), then click READY. 00:52:00
You removed The Equalizer 00:52:17
You added The Equalizer 00:52:19
You are ready 00:52:20
Dispenser 24: Please offer EXACTLY the following items: Any Weapon (Total: 1), then click READY. 00:52:24