I do a lot of crosswords so I needed some envelopes as my supply was running out. Found a company selling 500 for £28.67, I thought this sounded okay, looked into it a bit more and found an offer for buy one get one free. I jumped at this and got 1000 envelopes for £28.67. Do you think this was a bargain at 2.86 pence per envelope?
I tend to buy my envelopes in discount stores, such as B&M, where DL size envelopes (for A4, folded into three) work out at much the same price as you paid for your envelopes. i.e. 50 envelopes for £1.50 = 3p each:
https://www.bmstores.co.uk/products/dl-white-envelope-50pk-388269
So you paid a decent price but not greatly less than you might have paid on the high street.