We typically purchase 2-6 year old vehicles that have between 20 and 80k on them. Always looking for a good deal and when one presents itself we grab it and rotate one that is due. A lot depends on where it will fit in our business. We are currently looking for a LCF to suit our needs but the prices fluctuate so much and they usually have well over 100k and thats on a 3-5 or newer one.
Ultimately I would say purchase what you can pay cash for. You will always hate the vehicle if you are making payments.
What ever I do I must do it right!