Hi Cakeman,
In instances like this, where you want something that's available in a few labs, but not on the market, I'd suggest the following, in this approximate order:
1. See if your supervisor has ever collaborated with anyone who may have some, or know where you can lay your hands on some.
2. Get in contact with someone at your own uni who may have experience in production of this.
3. Consider contacting one of the authors of papers in your field where this fusion protein has been used - perhaps if you have one author who more commonly crops up in your work, you could try this.
4. Consider alternatives. I've never used, or come across, streptavidin-luciferase fusion protein, but I presume you want to tag something biotinylated with luciferase? Are there alternatives? For example, HRP-streptavidin? If this is a stupid suggestion, I apologise!
I'm confused as to why no one makes this commercially available...
Matt