Your definition of "Immediate delivery" and BFL's definition of "Immediate delivery" or "In Stock" etc. are likely very very different definitions.
A peek around the forums will show that in-stock ready for immediate delivery BFL's can still take Two WeeksTM
The Ebay ones would likely ship quicker.
Very true. My "in stock" unit took nearly 4 weeks to get here, ordered at the end of December.