When sourcing sterile Pasteur pipettes, the price is primarily driven by material quality (Low-Density Polyethylene - LDPE) and graduation precision. You should ensure the pipettes are shatterproof and have a uniform bulb suction force. For sterile applications, the integral bulb design is critical to prevent cross-contamination. Always verify the draw volume (e.g., 1ml, 3ml, or 5ml) and the drop size accuracy, as high-precision molds increase manufacturing costs but ensure experimental consistency.