Fire alarms

[bjorn]

I am looking for fire alarms (detectors) with a relay output so I can connect them to my home automation system. Some requirements:
<ul>
<li>Wired (don't want wireless)</li>
<li>Powered over the wire</li>
<li>Relay output (don't care if they are normally connected or normally open)</li>
<li>Decent price</li>
</ul>

Also nice, but not required:
<ul>
<li>Chainable, so that if one alarm goes on, all do.</li>
<li>Good looking, small in size.</li>
</ul>

A local store sells a model for something like 45€. The price is quite high compared to normal non-relay alarms, and they are quite bulky and not that nice looking. Not sure about the quality either. I am looking for an alternative.

And suggestions or experiences with alarms?