I use fibreoptic endoscopes for work, and have just got hold of an older Pentax 'scope for filthy cheap money, as it just needed a few minor repairs but didn't come with a light source.
~150W is the typical power level for halogen light sources for this purpose, but I can deal with less.
I have a fibre optic xmas tree and it uses one of these to focus light into the bundle through a colour wheel. Not as powerful as you wanted but maybe a cluster of them would do the job.
Do you actually focus the light into the fibre bundle, or just point the lamp at the end? My fibre connector has a 3mm diameter opening for light, hence thinking I need a little focus. Just wondering if a high power LED would do the job.
Something like this, driven with a 12V source.