Hey there,
That's not really a bug but a weird implementation. You already can't make the base price under 1$ but it's possible to sale it.
I would suggest to disallow sales for 1$ games (if they aren't in a bundle).
If you want to keep it maybe allow a maximum of 20% sale on 1$ games and allow them to proceed (normally the fees are around 30-50 cents with taxes) but I think that would be a harder implementation and even selling for 1$ isn't really worth it unfurtonately..
Thank you!