I use searches in ma-shops to gain a feeling both for valuations and assessment of condition.
The thinking being that the sellers there are professionals and know what they're doing. However, very often I find examples of entirely ordinary banknotes at incrediby inflated prices and/or with seemingly wildly generous assessment of condition.
My strategy to tackle this is to put my valuation near the cheapest end of the spectrum if there are multiple available and give it a range of 60-80% of that.
Are ma-shops a fair assessment of value (retail)?