I think the Chinatown one or the Paya Lebra ones is the
biggest.
Ok, knees length might be a problem.
I have about 8 pieces of jersey dresses from This Fashion, and
they after washing, ends just above the knees. And
considering I am short. Not sure will cover yours.
Your other alternative is always to shop at Robinsons Orchard or
even OG Orchards, which means the price is above the S$50/-
range.