I sent this link to a friend - stamp collector. She looked up the price - to buy unused and in mint condition the sheet of 70 stamps was $25. So the seller used $1.40 in face value for postage when she could have sold the sheet for 10 times face value. Friend didn't tell me the value once they're cancelled.
And all those blocks of 4 - :shock: You should be able to sell that envelope as is with all the cancelled stamps on it to a collector.