I have long been a proponent that sanctions must mean something. Mere slaps on the wrist do more harm than good. See here, for example. When it comes to monetary sanctions for attorney misconduct during discovery - which I have also argued is probably the most common yet least punished kind of attorney misconduct - I think the sanctions should be directed at the attorney - not the client and that they should be severe enough to cause the attorney to think twice about engaging in similar conduct in the future. How high the sanction should be to have this effect, however, I guess depends on the facts of the case.
One of these facts, according to the U.S. Court of Appeals for the Federal Circuit should be the lawyer's ability to pay. In ClearValue Inc. v. Pearl River Polymers Inc., (available here), the court threw out a monetary sanction that had been levied against an attorney for failing to turn over test results considered by a testifying expert. The sanction amounted to more than four times the lawyer's net annual income.
For more on this story check out this article in the ABA/BNA Lawyers' Manual on Professional Conduct. If you need a subscription to access the link, here is the actual cite: 25 Law. Man. Prof. Conduct 192.