We have tried to standardize on and have deployed a couple hundred 300-25’s. Given the lack of available inventory what are you using to replace them? Is it time to change models? Anyone have some they’d like to sell?
You might look beyond the normal suppliers. A Google search shows several that claim they have them in stock, including Amazon. The F300 CSM appears to be available through the normal suppliers, but you would have to use an external dish and they would be more pricey. There have been some coming up for sale on Wisp Talk Equipment (FB) but they go quick.