We grow mushrooms although not the same type as you -- we grow straw mushrooms. Our agent collects every day when we are growing and quite often he takes them to the market in Prasad ( Prasat ) rather than sending them to Bangkok with the bulk of his stock.
On a different note but in line with your posting, we have two unused 200 litre cool boxes ( we bought 3 when my wife opened her shop ) for sale. We are asking 2750 baht each. To give you some idea of price comparison, today at Macro Buriram we saw 200 litre cold boxes for sale... original price 4190 baht, reduced to 3990 baht. Your gf can ring the wife and chat about mushrooms etc., etc., on 0847667122 if you are still interested.