Print your own
Customizable DNA comb for Bio-Rad Horizontal Electrophoresis Systems. List price for these combs are $57. Shapeways is able to print these combs for about $5 each.
Designed using OpenSCAD, a free program for creating solid 3D CAD objects. The 3D model is generated using numeric values, allowing anyone to customize it and print their own custom combs. (No more tape to make larger wells!)
The preset model is specifically designed to work with Thingiverse's customizer tool. This allows the non-technical user to modify this model and make their own STL file for printing.
This model is configured to work with MakerBot's Thingiverse Customizer.