Get comfortable, this will take a while.
The "Parker-Style" ballpoint refills listed below have been tested, are easy to find, and extremely affordable. We update the list as we find more.

Pen Name/ Refill Name
•Faber-Castell Ballpoint Pen Refill (Parker Style Medium & Bold tip)
•Fisher Space Pen Refill (#PR4 with plastic adapter)
•Foray Gel Ink Refill (For Parker Ballpoint Pens)
•Moleskine Roller Pen Gel Ink Refill 0.5mm
•Monteverde Ballpoint Refill (For Parker Style Ballpoint Pens)
•Monteverde P42 Ceramic Gel Capless Refill (For Parker Style Ballpoint Pens)
•Monteverde Soft Roll P13 Ballpoint Pen Refill
•Monteverde Soft Roll P15 Super Broad Refill
•OHTO Needlepoint Ballpoint Pen Refill (P80-07NP)
•OHTO Extra-Fine 0.5mm Ballpoint Pen Refill (PS-205NP)
•Parafernalia Ballpoint Pen Refill
•Parker Ballpoint Pen Refill (Broad)
•Parker Gel Ink Quink Refills (Medium)
•Parker Quinkflow Ballpoint Pen Refill (Fine)
•Parker Quinkflow Ballpoint Pen Refill (Medium)
•Pelikan Giant Ballpoint Pen Refill 337 (Broad)
•Pelikan Giant Ballpoint Pen Refill 337 (Fine)
•Pelikan Giant Ballpoint Pen Refill 337 (Medium)
•Penatia Ballpoint Pen (Medium)
•Pentel Ballpoint Pen Refill (KFLT8)
•Schmidt 9000M EasyFlow Pen Refill
•Schmidt P8900 Super Bowl Refill (Fine)
•Schmidt P900 B Ballpoint Pen Refill (Broad)
•Schmidt P900 F Ballpoint Pen Refill (Fine)
•Schmidt P900 M Ballpoint Pen Refill (Medium)
•Schmidt P950 Megaline Pressurized Ballpoint Pen Refill (Medium)
•Schneider Express 735 Pen Refill (Broad)
•Schneider Express 735 Pen Refill (Fine)
•Schneider Express 735 Pen Refill (Medium)
•Schneider Slider 755 Pen Refill Hybrid Ink (Extra-Broad)
•Schneider Slider 755 Pen Refill ViscoGlide Ink (Medium)
•Sheaffer T Ballpoint Refill
•Stabilo Ballpoint Refill
•Tombow BR-ZLM Ballpoint Pen Refill
•Visconti Ballpoint Pen Refill (AA49 1.4 Broad)
•Visconti Gel Refill AA38B 1.0 Broad
•Visconti Gel Refill AA38F 0.5 Fine
•Visconti Gel Refill AA38M 0.7 Medium
•Yafa Gel Refills to fit Parker Ballpoint Pens

(The listed refills above are sometimes re-named or re-numbered in different parts of the world by pen refill companies. We can’t list every possible name change so we suggest you use the info above if your country/region calls the pens/refills something else.)

All brands, logos, and trademarks displayed and/or mentioned are used for informational purposes only and are sole property of each respected company and owner. No endorsement or ownership implied.