Picked this up at an estate sale for $25. Cross Fountain Pen 1/20 10kt Gold Filled. Flushed it, tested it out with a cartridge (it comes with a converter), and worked great! :
Amazon.com : Cross Century II Refillable Ballpoint Pen, Medium Ballpen, Includes Luxury Gift Box - 10 Carat Gold-Filled : Rollerball Pens : Office Products