Check the manufacturers website of the product you are looking at and they will, in some cases, tell you if the online/ ebay retailers are authorized.
Many times you'll find they are not, which makes that warranty deal a lie. The seller offers a "warranty" which may or may not be worth the paper it is written on or more. The truth on consumer electronics is this...the manufacturers set a minumim retail price for their dealers, and they can't/wont' as a general rule go under that price.
Also, remember...very little depreciates or gets outdated as quickly as electronics. I like music as well, am a wanna be audiophile, and have sorta decided to just bite the bullet on home theater stuff. When my good stuff dies, I replace it. I get a lot of use out of it. The new stuff out there in the A/V Reciever lines are amazing "switching centers" for input systems...lots of HDMI inputs, conversions, soundstage options and true 7.1 sound. Do yer reserarch and bite the bullet.
Crutchfield is a great place to get a look at your full-retail number, watch the end of year sales at places like Magnolia and Frys, and any legit online dealer, and pull the trigger when you find a good price. I have had very good luck with Yamaha A/V Recievers.