In my opinion, investigationa should be done wherever the trail leads. I'd prefer an independent investigator with no political ties to the Bush administrations {both Bush administrations, father & son}or to the {Bill} Clinton administration, the Obama campaign, the Hillary Clinton campaign, and/or the McCain campaign.
And yes, it would cost money. But I believe that it would be worth it to restore a measure of faith in [another] United States system that apparently is broken.