I believe Maggette signed a 5 year/$50MIL deal which has been questioned by many people on ESPN since Maggette's only other offers were for the MLE.
Chris Mullin is the modern day BK. He can spot talent, but he often sets the market by bidding against himself (see: Foyle, Adonal). The Maggette deal is practically a sign of restraint compared to Foyle's contract.
Back to potential Iggy deals. The question is not really one of the market today setting the market value when evaluating whether to match a contract. It is easy to say it is a market price because that is what the market offered, but the market often has outliers and those are the "market" deals you need to avoid (kind of like buying the stock market last September with a five year retirement outlook). If any player signs an offer sheet, the evaluation of it has many facets beyond the current market, including the following:
1. What is the cost of the contract vs. the likely cost in money and other assets to obtain a similar level of productivity from another source?
2. What is the likelihood that this player/contract can be moved for value fairly equivalent to the player's abilities/contributions in two years (after BYC stops being a problem)? If the contract will significantly impair the player's trade value as compared to their productivity, then it is a bad contract. In two years half of the teams in the league will have tons of cap space. Very few will sign LeBron, Wade, Bosh, Amare, etc. Iggy's contract, even at $65-70 million total will be attractive to the teams that lose out in FA that year assuming he stays healthy and productive.
3. How will the contract affect your team's financial flexibility/luxury tax situation vs the player's productivity this year, and for the next three years?