BIN price or negotiation? That’s just one example of a question you should be asking yourself and to find the best solution for your portfolio (I don’t think there’s a “one size fits all” solution because each portfolio is different and each domain owner has a different financial situation, different expectations and so on), why not split test?
Each approach has its own pros and cons (for example, BIN pricing requires less involvement on your part but on the other hand, you’re increasing the likelihood of leaving money on the table), split testing basically helps you find the best solution for your specific situation.
Of course, if you can compare results with other domainers, even better.
The bottom line is this: no matter what industry you’re involved in, you shouldn’t underestimate the importance of split testing. Test, test, test and test some more: have fun