When a piece of legislation is brought before a legislative body (either the House or the Senate), it is nothing short of bribery to vote swap (i.e., I'll vote for your bill if you vote for mine; or I'll vote for your bill if you give my district X dollars via an unrelated amendment).
Two rules could fix this:
1) No off-the-record conversations about pending legislation (ex parte communication). It is simply unfair to the legislative body as a whole for cabals to be formed based on matters completely unrelated to the legislation at hand. The only exception should be public meetings (such as townhalls) in which the public and press have been given ample notice.
2) No quid pro quo arrangments for votes.
If the above two behaviors were reduced significantly, the incentives to soak the taxpayers would reduce significantly.
Lastly, and maybe unrealistically, each legislator should disclose (on the record) all of the financial incentives at stake for each vote. For example, if a legislator's relative works for a lobbying firm, this should be disclosed prior to the legislator voting and certainly must be disclosed if the legislator makes a speech regarding a piece of legislation.
This would save untold amounts of money by eliminating the underlying incentives to pad the budget. Currently, there is no strong dis-incentive to individual legislators to request more money from the taxpayers. This idea would at least undercut the incentives for enabling this behavior. Vote bartering and ex parte communication are enablers for fraud, waste, and disengenuous legislation.