Amazon has the Fisher 400B Space Bullet Space Pen in black for just $16.45 (Reg $22.00) with Prime Shipping. It writes at any angle, even in zero gravity and writes in extreme temperatures ranging from -30F to 250F.
If you are not already a Prime Member you can join with a 30-day free trial of Prime, as a student with Prime Student, or as part of Amazon Family.
Please note that Amazon prices are subject to change at any time and may have increased or decreased since this offer was posted.