Boots

I have often bought shoes at ninewest.com.

zappos is very very expensive. it's great that it offers free shipping and free returns but you will not get a deal there.
what kind of boots are you looking for? if you're looking for something general here try smartbargains.com if you do find something you like in this site don't check out just yet. put whatever you like in the cart then type www.google.com and in the search box type smartbargains.com and the first site that is offered is smartbargains.com via google checkout. this way you'll get free shipping and 10 per cent off (on top of whatever sales the site already has).
second, www.6pm.com it never offers free shipping but stuff is much cheaper there. 6pm gives deals every day so just check the site every day and see what deals they're offering. i usually get my 'bdand' name stuff through here when they have those 75 per cent off or 80 per cent off something i already want.
if you're looking for snow boots
landsend.com
i only buy lands end boots. best and great prices.
if you choose to use landsend before you order go to retailmenot.com in the search box type landsend.com and get coupon codes for free shipping.
now if you were to get a bit more specific as to what you're looking for i may be able to offer more

I trust Zappos.com. And I rely on the customer feedback in regard to how the boots actually fit people who bought them before. You can find deal there, in the sale section. I just bought a pair of winter boots for $79 marked downfrom $150. But if you got outside the sale section, it can be expensive since the cost includes the "free shipping".

I've bought from Macys.com too, but the customer feedback isn't available like with Zappos and more often, I have to return them.

I just recently bought a pair of boots for my daughter on amazon.com. I order there a lot and never had any issues.

I was in DSW not that long ago and they still had plenty of boots in the store. But if you want to go the online route, I'd reccommend Zappos, DSW or Piperlime. I've bought shoes from all 3 sites and never had any issues. (FYI- zappos is owned by Amazon and Piperlime is owned by the Gap)

A.,
You might also try shopittome.com.