shoes
Having reasonable footwear for tango can make all
the difference, particularly something that's
comfortable to move in and let's you pivot easily
on the ball of your foot. Sticky shoes (or bare feet
on the wrong floor) can make this hard to do,
and give your knees problems.
Although it's common for followers to wear heels,
and you certainly may, they are not necessary.
For practices like ours I recommend dance sneakers
or character shoes, as described below.
online

The Sansha Salsette is a nice dance sneaker for tango,
with a suede sole which pivots well.
$30 from Amazon. (The sizing is odd; men should order about 3 sizes larger than your regular shoe size.)
If instead you'd like something with a heel,

Amber has found this
New York T-Strap
2" heel character shoe very comfortable,
for under $40.