You could make the argument that we already spent the RVP money, whatever it might end up being, on his direct replacement(s) - Giroud and Podolski.
But yeah, the bottom line is that we spend next to nothing in net terms on transfers. While that means we are well behind most other teams in the premiership, it also would indicate that we use the money on players sold on more players. Though it may seem like it, we aren't pocketing £20m a year on transfer fees. By the same token, we aren't chucking in an extra £20m per year either.