Why is Milorganite so expensive now?

I've noticed that Milorganite, a popular fertilizer, has become significantly more expensive in recent times. Can you shed some light on the reasons behind this price increase? Are there any supply chain disruptions or changes in production costs that are contributing to this trend? Additionally, are there any alternative products that offer similar benefits but at a more affordable price point? Understanding these factors will help me make an informed decision about whether to continue using Milorganite or explore other options.