Well, the post office has done it again....raised the price of sending something via the USPS. And since their last raise, just over a year ago, things have really gotten complicated in terms of sending things thru the mail. Take your #10 envelope. Just plopped on a .42 cent stamp and you should be good to go....as long as it is 1 oz or less and is less than 1/4" thick. If any of those variables change....say your sending something bulky or multiple papers that make it thicker than normal, they charge additional postage for BOTH the weight increase AND the fact is a "non- machinable" envelope (basically someone has to hand cancel and code it).
So why bring this up? Well, I can't image a more complicated envelope to send thru the PO these days than wedding invitations . With bows, wraps, bling and other items affixed to modern invitations, trying to figure out and budget for the postage is quite the job! Since most people figure out their wedding budgets soon after they get engaged, buying an invitation some 6+ months later can completely throw your budget completely out of whack!
I just recently had a client come by to pick up their envelopes that I had addressed. She gave me some stamps to send some envelopes out that needed to be re-done and I commented on the .90-some cents it was costing her on each envelope. She said "We needed additional postage because the envelope was considered large AND non-machinable. On top of the response envelope stamp, it cost her OVER $1.40 per invitation to mail them. With 169 invitations to mail...well, I think you get the picture.
So, a word to the wise when creating your invitation budget....plan for the most amount of postage possible. Remember to keep in mind that square envelopes, over-sized envelopes (anything larger than 6.25" in height) and over 1/4" thick will trigger additional postage costs. If you end up going with the traditional invitation, at least your budget won't have suffered. But if you go with a fancier, less traditional style of invitation, your budget can allow for it and everyone will be happy!