Kinetic binding / unbinding constants of protein + mRNA ⇌ mRNP
Ridgeway and coworkers designed a really neat microfluidic device for making these kinds of kinetic binding measurements on RNA and protein (Ridgeway et al. 2009). Their device works sort of like a stop-flow, and they used a FRET based scheme to detect binding and unbinding events. They took measurements for one particular rRNA/ribosomal protein pair and got (6 ± 0.4) × 105 M-1s-1 for the bimolecular on-rate kon and  (5 ± 0.9) × 10-3 s-1 for the unimolecular off-rate koff.

Ridgeway cites references 23,24,26, and 33 when talking about experiments with "similar constructs and buffer conditions", so those would probably be a good place to start looking if you want to assemble a diverse set of kon  and koff&nbsp; values.