Shuellas are available in a variety of colors, including black, of course. They are regularly $49.95, which includes shipping; for a limited time (now through April 24), you can get them for $34.95, including shipping, by entering the Shuella website through a special Daily Candy reader link, which I am revealing here.
And, to put under your Shuellas, check out Naturalizer's "Diverse" pumps (pictured left). I definitely categorize these pumps as classic, conservative, professional -- 2 1/4" heel -- great for pants suits that will cover the ultra-conservative criss-cross straps at the top. They are made from a fabric upper; the remainder is synthetic (though, I can't vouch for the content of Naturalizer's glue). Originally $69.95, onlineshoes.com is offering them for $59.99, including free shipping. Find them here.