I found out that there is no beeper on some Routerboards.

I trashed a bunch of RB750G routers when I found out that the beeper is missing.

You seriously trashed them?! I would have gladly taken them off your hands.

You seriously trashed them?!

Seriously, no I'm not insane (not yet).

A word of warning, don't cheap out like I did. For $30 more, you'll get these features if you buy RB450G:

RB450G

1. 256MB RAM
2. MicroSD card slot
3. RS232C Port
4. Temperatur Sensor
5. Voltage Monitor
6. Level 5 license
7. Beeper

RB750G

1. 32MB RAM
2. No MicroSD card slot
3. No RS232C Port
4. No Temperatur Sensor
5. No Voltage Monitor (not working)
6. Level 4 license
7. No Beeper

Okey, I purchased RB750G instead of RB450G, so I'm insane.

It doesn't say anywhere that the RB750G has a beeper. Why do you need a beeper anyway?

I use the beeper as alarm, it's very useful.

A word of warning, don't cheap out like I did. For $30 more, you'll get these features if you buy RB450G:

Don't forget another $15 or so for case and power supply + labor for putting it together.
When buying a few hundred units the difference really adds up.