There is no TurboTax fee involved.  There is a difference in the fees depending on whether you file for an installment agreement online directly with the IRS or use Form 9465 to establish the agreement with the IRS.  There can also be a difference in the fees depending on how you choose to make payments, i.e. direct debit plans are given a reduction of fees.  TurboTax's fee reference is for the regular installment agreement using Form 9465.  You can view the full list of fees at the link below (scroll down the page).  It looks like $31 is the current pricing for an online agreement with direct debit.

https://www.irs.gov/individuals/payment-plans-installment-agreements