Having your DNA tested through Ancestry, 23andMe, or Family Tree DNA is worth the $ if you are doing more than ethnicity searching. If you are struggling with a genealogical brick wall or want to see what you might be genetically predispose to then it is worth the price. Like the others posted earlier Ancestry usually has a 30% sale around Black Friday. And like posted earlier you can then upload your DNA results to GEDMATCH.com for free to see more information. There is also a site called
Promethease where you can pay $5 and upload your DNA results and they will give the most extensive genetic medical information about yourself that I have come across. It is worth reading reviews on DNA testing and check out reviews on Promethease before you decide. Also, interesting tip I learned from Ancestry - Having Native American show up on your list can mean that you are descendant from any of the Native American tribes from Canada to tip of South America they do not distinguish anymore than that.
Warning genealogy can be addictive.