Registrars currently pay VeriSign a base registration fees of $6.42 for .com domains and $3.85 for .net domains.
Beginning in October the prices will increase to $6.86 per .com domain and $4.23 per .net domain name. Coincidentally, this is the maximum 7% increase allowed under the terms of VeriSign's contract with ICANN. The contract currently runs until 2012.
There is little doubt registrars will pass the costs on to customers.
If VeriSign continues their annual 7% increase, registrars will be paying $9.00 per .com domains by the time the contract ends in 2012 -- an increase of 50% in six years.
VeriSign has a press release justifying the price increase that can be found here [verisign.com].