Much like with my first motorcycle, gearing up my BMW has been an educational experience. The first thing I've learned is that there must not be that many people that take an R1150R for long trips, because almost no one makes decent luggage for it. Fortunately, since my bike is 3 years old, there's a great forum where other people have spent several years figuring out who makes luggage that fits, and which works the best.
As it stands now, I'm just ecstatic that I finally found a Hepco-Becker rack for their top cases that will actually work with my factory luggage racks. I just wish I could get as lucky with finding some used BMW system cases. Every time I find some on Ebay, someone who has never bought anything starts driving the price up at the last minute. While I'm more than willing to pay $400-$500 for plastic saddle bags if they're in good condition, I'm not keen on people that look like they're probably just shill bidders.
Fortunately, since my first real trip isn't until June, when I head to Nova Scotia, I can probably hold out until March before I finally have to suck it up and pay retail for a new set.