The definition of a "good" cost per result in Facebook ads depends on various factors such as the industry, target audience, geographic location, campaign objective, and advertising budget. Moreover, the term "result" can differ based on the campaign objective, ranging from post engagement, page likes, link clicks, video views, conversions, etc.

To determine what is a good cost per result for your specific campaign, it is recommended to consider the following steps:

1. Define your campaign objective: Determine what specific result you want to achieve through your Facebook ads campaign (e.g., conversions, engagement, traffic, etc.).

2. Benchmark data: Research industry benchmarks and competitor advertising to get an understanding of typical results and costs within your sector.

3. Historical data: Look at your past Facebook ads campaigns or similar campaigns to gather data on the average cost per result you have achieved previously.

4. Set a realistic target: Based on the above research and historical data, set a reasonable target for the cost per result that aligns with your campaign goals and budget.

5. Monitor and optimize: Continuously monitor and optimize your Facebook ads campaign to improve performance and lower costs. Make adjustments to targeting, ad creatives, budgets, or bidding strategies as necessary.

Remember, what is considered a good cost per result can vary widely depending on the factors mentioned earlier. Consequently, it is crucial to set your own benchmarks and goals based on your specific circumstances and industry norms.