Have you discussed requirements with their account managers? They can be a little more creative than their list prices when they realise you don't have the budget for the data you ideally need but are a potential source of recurring revenue. And the EO market is getting more competitive...

If you are looking for evidentiary purposes, does the Sentinel-1 + Nimbo data give you enough to filter the forest-wide data down to specific areas of interest you might want more spatial/temporal resolution? (or as a former colleague once put it when looking for evidence of more localised and heterogenous environmental damage "to find the needle in the haystack, you first remove the haystack"). Particularly if identifying specific areas of interest is a potential route for you to escalate to another party with an active interest and bigger budget...

Your other route to the commercial data you ideally want would be via partnership with EO consultancies with publicly funded R&D projects to showcase their capabilities (easier if you're European, but not a prerequisite). ESA, for example, devotes a lot of funding for private consortia to demonstrate that Copernicus data (coupled with other data where necessary) yields useful results...

It's a while since I worked in this field (in a non-technical role) but happy to share what I learned in more detail - email in profile.