If I understand Intrade a contact doesn’t cost much. Depending on how many contracts are out there, a few folks could move the percentage anyway they want.
However, the important part is the outstanding number of contracts. For the state-by-state electoral votes, the total volume is pretty low, especially in comparison with the contracts betting on the outcome of the general election.
The battleground states have the highest volume, but even those could be temporarily swung one way or the other by someone with enough money to burn. However, they would soon swing back, when someone seizes the opportunity to make some money.
Again, the trend (over weeks and months) is what is important. At the moment, the absolute numbers are not useful, especially for a close election.