Refilling Rollerball refills

I hate paying $5 or so for Retro51 rollerball refills, so I decided to try
refilling one to see what might happen.
Pulled off the cap opposite the point of the refill using pliers. It came
off easy. Down inside seems to be a fibrous insert that holds the ink, and
helps regualte the flow. Leave it in place.
I used a super small hypodermic syringe with a tiny needle, filled it with 2
cylinders full of Waterman black ink (just because that was the only black I
had on hand), pressed on the cap again, easy also, and screwed the refill
back into the pen.
Works perfectly: a black, lustrous line, that doesn't blot or skip. I am a
happy camper. There seemed to be no wait time before the injected ink did
the trick either.

Now, has anyone found a cheaper, generic replacement refill for the Retro51
?? The generics from Staples seem close, but are about 0.5mm too short, and
tend to trap the spring also, otherwise, at three for $2 or so, they are a
deal.

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Neill Currie
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USA
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