Representative pricing for multiple sources including Planet's RapidEye: http://www.landinfo.com/satellite-imagery-pricing.html

Purchasing a before and after image of a specific logging site isn't cheap once you've factored in minimum order sizes, but it isn't unaffordable. Purchasing images to look at deforestation on a national scale (if you're looking at individual trees, not woods; open data will give you the latter) is millions of dollars per annum, but worked very well where tried to prevent illegal vegetation clearing in Australia.