iPod dock connector cover (old connector)

My iPod dock stereo is in a fairly dusty area, and I only use it at the weekends or thereabouts, so a bit concerned about the connector getting dusty and shoving dust up into my iPod classic.

I'm looking for a neat solution that will just cover the dock connector, something cheap and plastic but I can't for the life of me think of something suitable.

Basically it needs to roughly have the following qualities:

- Be black
- Roughly 3 cm wide by 1 cm deep, by 1 cm high.
- Less than €1 (not one of those pricey ones I see on ebay!)

Was thinking of something like the cap that fits at the bottom of some chair legs.