Why not run every shirt by suedehead to get an idea of value? It's what I did with every shirt I sold and his input was invaluable. If a shirt is worth no more than £10 or so, than the Cabin is the place to sell, otherwise a higher price should be put on it, whether that's then sold via the Cabin, eBay or another medium. Obviously suedehead would need to agree!
We owe it to the people who donate to get the best price possible. That's not always been the case, as I know from experience. Programmes with real value have been sold for peanuts and yet my offer to go through donations and pick out the nuggets was strongly rejected.