Lots of nice oysters around for under $10 at various lighting stores, especially the ones I see that have been closing down for the last 5 years or so
Since you love downlights Fernfurn but don't like the heat, you can go for leds...
that being said, there are very high power leds around which do get hot, and the heat produced by the transformer is based on how much load/how many lights it's running, and also by how well it's made. You could setup nice cool running led lighting, but won't be anywhere as cheap as oysters!
Leds are very long life as well, up to 100,000 hours is common so they could last a lifetime in many rooms (around ~11.4 years if you left them on 24/7) and the very high power ones can be around half that, which is still good! Leds are easily blown however, from things like power spikes or power supply/transformer faults

Quality power supplies will avoid these problems, but yeah, that could get expensive.
http://www.google.com.au/search?hl=...a=&aq=0&aqi=g10&aql=&oq=led+lighting&gs_rfai=