Seamasters are a line of watches from the "Omega Collections" which have been very popular over the years especially since 007 started wearing them in the famous James Bond movies.
These watches are available as a quartz (battery) or an auto (mechanical) version.There are several models and the novice would be well advised to visit the official Omega website to check out the different models.
The reason for this guide is to stress that being very careful is the key when dealing with these watches as this model is very often copied and sold through Ebay.
I would love to go into details but space would not permit however remember that there is no such thing as a bargain.Omega watches are of a high quality and a watch with all paperwork,cards and boxes will normally command a better price than one that doesn't.Just because it has the above items doesn't mean it is genuine.There are many fake boxes etc out there.
I would recommend joining a watch forum and posting a link or a picture of the watch you are considering as many members are very knowledgable and are only too happy to help.
Another point is to ask the seller to post a picture of the watch with a date and time nominated by yourself on the watch's face to verify that it is the watch that you are bidding on.(I have a friend in the US who is a well known watch photographer and I quite often see his photos used in listings.)
As I said earlier that there are many details to look at and not enough space here,exercise caution.If in doubt miss out!Omega watches are high quality and feel high quality.Check the sellers previous feedback and look for strange goings on.High feedback may not mean sales of high ticket (priced) items.
Also check out Ebay's guide for payment as some offer better security than others.
Thanks for looking and enjoy your watch.