Blockbuster Video or Hollywood Video might have anime available to rent, but in my experience, it's usually not a very big selection.
Barnes and Noble, Borders, and Amazon all have huge selections of manga, and both Amazon and Barnes and Noble's websites have a large of selection of anime DVDs you can order. Amazon also has a lot of anime soundtracks you can order. If there's a Suncoast Motion Picture Company store near you, they might have a large selection, as might Best Buy (at least, they do in my area). FYE/Spec's music stores also tend to have an anime section, but be careful there, since they also sell some of the 18+ stuff and put it on the same shelf (but they are clearly labelled). The rest of the stores I mentioned hide that stuff away so nobody sees it, thank goodness. Finding anime on eBay is really only good for ordering used Japanese laserdiscs or imported Japanese DVDs without subtitles or bootlegs from Hong Kong that have horribly-translated English subtitles (if you ever see a supposedly Japanese imported DVD selling for around $25 USD or less and has English subtitles, 99% of the time it's a bootleg. If it's an entire series, like say, Inuyasha Season 1, but it's on only three discs (instead of the seven or eight discs it normally would be in America or Japan), selling for about $50 USD, that's also probably a bootleg. Internet retailers are notorious for this, but if you go to a reputable source, like Barnes and Noble or Amazon, they'll sell you the real thing, as will the store I mention below).
For true-to-the-source Japanese imports, cdjapan is the best one, even though you'll have to fork over the extra money to actually pay the Japanese retail price (which is usually much higher than the American), and then the shipping and handling on top of it, and you probably won't have any sort of subtitles, but those DVDs should have much higher video quality than the US releases since there aren't as many episodes packed onto a disc and more of the disc's storage space can be used for one episode (kind of like the difference between VCR recording modes). And many of those series have been rereleased in remastered form in Japan but not yet (or possibly ever) in the US or other countries. cdjapan also has a larger selection of anime soundtracks and normal jpop and jrock cds than Amazon does.