I recently obtained a bargain - a Montague Paratrooper http://www.montaguebikes.com/folding-bike/ for $32 and a cup of coffee.
By the time I got it home, grit blasted, powder coated, went through the components under a kero bath, replaced worn components, replaced more components, bought wheels to replace the ones I couldn't transport back, updated some bits and pieces, upgraded some comfy bits, pretty muck built up an equivalent Montague X90 (same frame set), etc, etc, my bargain cost me pennies over £1300!