A poorly designed and unusable system can lead to immense frustration to users, reduced productivity, undesirable profit lose and deterioration of one's quality of life. To determine a successful interactive system, usability should be integrated in the design process to ensure greater shifts in efficiency and help to reduce work task errors. Incorporating usability in the development process can help to bridge the communication and procurement process for suppliers and customer organisations. Two usability evaluation methods, usability testing and heuristic evaluation were employed to evaluate on an online shopping website, namely Prezzybox.com. The main difference of these two usability evaluation methods is: usability testing involves real users in the test; whilst heuristic evaluation is a 'quick and cheap' technique to evaluate user interface with reference to a rule of thumbs by experts. Cost-benefit analysis was also carried out to justify which usability evaluation method was more cost-effective. The effectiveness of Common Industry Format (now as ISO/IEC 25062:2006) industry-reporting format for both usability evaluation methods is also discussed.