importcds.com (sometimes their own web site is a better deal than amazon marketplace version)
In my experience, the nominal prices are usually similar, but their website discounts on shipping for multiple items. They also have site-wide sales a couple times per year.
Classical Music Superstore on alibris is similar. They don’t have sales as such, but alibris almost always has a coupon.
Aside from saving a few bucks per order, I think there is value in supporting alternatives to the behemoth.