Old political buttons are a great way to own a piece of American history, and they can be very reasonably priced - but there a couple things to watch out for:

1) About half of all the pins on Ebay are REPRODUCTIONS, not the genuine pins from the election! Several companies made and distributed tens of millions fo reproduction pins (usually one for each major presidential candidate in each election). The most common seem to be the 1968 Kleenix set (and '72 Crackerbarrel version of this set) and the 1972 American Oil set. You can often find auctions with the entire set of reproductions on ebay (labeled as such by good sellers) and it is useful to look at those pictures - if a pin is in a repro set it is almost certain (over 99/100) that other pins that look the same are also reproductions. For a comprehensive look at reproductions and other fakes, you can look at Brummagem: An APIC Project: A Handbook on Fakes, Fantasies & Repins http://members.ebay.com/ws2/eBayISAPI.dll?ViewUserPage&userid=american_political_items_collectors, a free PDF on all the known fakes and reproductions from the American Political Items Collectors group (APIC), available on their website.

 If a seller is a member of APIC, is a good indicator that they will not knowingly sell a reproduction. It also helps to look at the dealer's feedback and see what else they have sold - if they have sold a lot of different pins to happy buyers, they likely know what a repro is and will not sell it. Be wary of dealers that sell mostly other items, even if they have great feedback - many reproductions are listed by people who do not know they are listing a reproduction (there are lots in ebay stores also).

2) If you find a pin and are thinking of selling it, make sure it is legit FIRST! It is actually a violation of federal law to try and pass off fake/repro political memoribila as real, and you risk your good name, feedback, and your listing fees. Once you can recognise the reproduction sets, you will see that about half of the button listings (not counting regular dealers) are for reproductions (usually with no bids).

3) If the auction says "I am not sure if these are reproductions or not" then they ARE repros and the dealer knows it.