I will say the last few parts of your criticisms seem highly unnecessary - because the IF is currently free (and free games or books etc. will be quite unprofessional) also most IF authors I've seen who charge anything have a patreon (that the author doesn't have) which you opt into for bonus content
The most I've seen an IF go for is 12$ (I think authors deserve more but that's besides the point) and that's on the high end
Which is all to say whatever prices the author 'would' charge you'd get about what you'd pay for but the author isn't charging anything so it's not worth speculating on