Since the Drug Discovery Resources page on Distribution and Plasma Protein Binding is one of the most frequently read I thought I'd mention a publication from the Univ of Washington DOI describing an inexpensive Microdialysis Device for Measuring Drug–Protein Binding (DIYM).

The device is based on the standard equilibrium dialysis method to measure the fraction of low molecular weight compound bound to proteins. It is constructed from a standard polypropylene 96-well plate, dialysis tubing, and low viscosity epoxy resin. The device can be readily prepared for a small fraction of the cost of a commercial, multi-chamber, micro-dialysis device.

The results obtained agree favourably with literature values.