I gave up on IRC's over a decade ago. The last batch I purchased via mail from the local post office. They always had a fit when I went to the counter, I held up the line while they stamped them. The last batch were stamped on the wrong side, when I took them back they, at first refused to refund my money or replace them, the clerk said once stamped on that side they were worth only one domestic airmail stamp. Got really bent out of shape when they told me some I had were out of date, they were carefully marked "No Expiration"
Used to buy at least one sheet of each commerative as it was released (starting in the late 50's). By the 80's they were releasing commeratives at a rate that made the European micro states look like pikers. Not long ago I decided to sell off a lot of them. Most of the offers were less than face value. So I have been using them for postage (now that sure doesn't help the post office out of its current problems).
In The late 1990's I stopped at Bill Plumb's booth at the Dayton Hamvention and purchased two of his stamps in an attempt to get two outstanding cards. Got both cards in a few weeks and have been using his stamps ever since, in most cases the country stamp was cheaper than an IRC.
Returns are over 90%