It depends who you're flying as each of the lounges that offer paid access have carrier requirements.

If you're flying a oneWorld alliance member (e.g. AA or BA) you may be able (subject to availability) to purchase access to the American Admirals Club in T4 or T5 for $65 or the Flagship Lounge in T4 for $150. You may also be able to purchase access to the Alaska Lounge in T6 for $60.

If you're flying on a Star Alliance carrier (e.g. UA) then you may be able to purchase access to the Star Alliance Lounge in TBIT for $75 or the United Club in T7 for $59.

I'm not aware of any of the Skyteam Lounges that offer paid access. The Delta Skyclub does not offer single visit or day passes to people who are not eligible for entry (guests of people with access can pay $50).