I don't have enough experience about India to comment on that but in the US the amount of money it takes to influence a politician is quite low.
Don't you need to donate at least $100k to influence senators or influence party positions in the US? Sure, you could "buy" a politician for cheaper, but you're not guaranteeing they will toe your line.
India is ridiculously expensive - bribes often amount to 50 lakh rupees to 1 crore + rupees, which amounts to roughly $50k-100k per politician. Not to mention bribery at the lower rungs of the ladder where everyone from the politician's toilet janitor all the way to the politician's chief of staff will demand their pound of flesh, usually in the tune of tens of lakhs of rupees (~$10k).
How much do you estimate it would take to get a politician to flip their view on abortion, gun control, illegal immigration, health care? Seems like if it were "quite low" you'd see politicians flipping views all the time as one side or the other channelled money to them.
What we actually see is a lot of stasis, refusal to compromise, and politicians locked in with their party, which suggests it is pretty hard to influence politicians.
Where money is effective is using it to get politicians who agree with your view elected.