I just use a Facebook page dedicated to buying and selling leotards. I generally sell ours between $10-25 each and have bought them in the same range. I have yet to have a problem with leos, as all sales include pictures, sizes, brands, and usually end even measurements. I did get burned once buying a gymnastics shirt from the page. It was labeled as AM and advertised the same, but it had to be a child XS by measurement. It wouldn't fit my DD if it were twice the size and she's around 5'5 and 115 pounds. It was only $7 though, so I chalked it up to a learning experience (get measurements for clothes too!) and donated it.