I have in the past seen frozen Montmorency cherries (tart pie cherries) in big bags, maybe four pounds, at the Sara Lee outlet at Western & Granville. Have not been there in a while but a person could inquire. Another source was the Super-K at Lincoln & McCormick but I think they went out of business---possibly another Super-K would carry them. Also, there is an online source called Cherry Stop that sells a 20-oz. bag of frozen cherries for $4.25 but I imagine the Fed Ex charges would be interesting. What would be wonderful would be if we could convince Trader Joe to carry frozen Montmorency cherries: let's all start bothering them about it.
Related to this, black raspberries are now nearly extinct in Chicago. Yesterday at the Near North Farmers' Market there were a few @ $4.50 pint. Turns out there is a wholesale source of IQF (individually quick-frozen) black raspberries---this is the Oregon Berry Packing Company (online). I emailed them to ask about retail purchase; they aren't set up for it but gave me the name of "Eddy" at Coloma Frozen Foods, phone 1-800-642-2723 who I guess conveys the berries to retail outlets. Again, wouldn't it be nice if Trader Joe would carry these---or if anybody would. If another Chowhound wants to join me in a dedicated quest for a Chicago retailer who will stock frozen Montmorency cherries or black raspberries, please email me direct so we can coordinate our efforts. This sounds do-able to me. A source of these hard-to-find fruits in IQF form guarantees a year-long supply of pies and cobblers.