I am looking at the need to have inguinal Hernia surgery in Chiang Mai.

Two options seem to present themselves: In-Patient and Out-Patient. Out-Patient would seem to the least expensive.

Who, and at which hospital would recommend? At what cost?

Is there a significant difference between the Contract Rate an insurance company would pay versus an individual?

There is a vast difference in the US, with contracted rated often as much a 40% of what an individual without insurance would pay.

Should I buy insurance and wait out the 6 month "pre-existing condition" period?

Thanks in advance for your considerate responses.

If you purchase Insurance and the condition is determined to be pre existing even after the waiting period has passed may result in the claim being rejected, the policy could also be canceled and other legal action could be taken by the insurance company against you.

Above is correct. I suggest you not even consider doing this as it could jeopardize your ability to ever obtain insurance in Thailand, which you -- and everyone living here -- need to do. Go ahead and bite the bullet paying for the hernia repair yourself and then take out an insurance policy, accurately presenting your medical history on it. The fact that you will have had a hernia repair is not likely to weigh much against you as it is not a chronic condition. Worst case, they may exclude that one condition from the policy (altogether or for a period of time after the policy takes effect).

Medical insurance is something to take out before you need it, not after. Be thankful that at least what you need now is comparatively minor. Some people only wake up to the need for insurance after faced with a catastrophic illness or injury, at which point they are seriously screwed.

In terms of the private pay cost for the hernia repair, your best option is Chiang Mai University Hospital (I forget the actual name). You can consult a surgeon at "Sripat", the private outpatient wing of the hospital, and then get the procedure done at the hospital. It will likely not be too expensive as it is a government hospital.

Because the daily room charges at a government hospital are quite modest there will probably not be much difference in cost between in and outpatient, and in fact they do not do much outpatient surgery in Thailand. Odds are they will ask you to stay at least a night in hospital. The biggest cost will be the surgeon and anethetist's fees, one day more or less in hospital won't make much difference.