Wedding-themed stamps are available through many websites and craft stores that offer Scrapbooking supplies. A good start would be to ask at your favourite store or search on your favourite website.
One can buy wedding stamps from stores like Superstore, Wall mart, Target and many more. One can also purchase them online for cheap and free shipping.
The post office is probably the best place to get wedding stamps as they have a few different ones although it might be a bit more expensive than normal stamps. One can get them online too at Ups.
ebay
You can buy it at any store :)
You can buy stamps online at www.Stamps.com
One place you can find wedding invitation templates is at Zazzle. There you can also add your own photos and text, and they even have stamps that you can customize with you and your significant other's photo.
An easy way to find good value for your stamps is to buy a stamp magazine. Linn's is a good one.
No they will not buy back stamps
You can buy stamps at Office Max or Cape Henry Hardware.
Stamp collectors, they refer to themselves as philatelists or people who study stamps, buy used stamps. They are not likely to want to buy one or two stamps unless they are particularly valuable. People often buy big bundles or packages of stamps because they enjoy sorting through them and identifying them.
you can buy coupons at the post office that are redeemable in foreign countries for stamps
You can buy online from Addprint Rubber Stamps