The average age limit I found was 10 years - including my credit union. There will always be exceptions to that, as noted above.
The personal loan, home equity, etc. is one way to get around that limit.
For me, as crasster suggested, I bought old enough so I could pay cash. Then what I would have made in loan payments, I put back into my savings. Basically I borrowed from myself at 0% interest. That has made it much easier to handle unexpected repair costs because I can waive my "monthly payments" to myself without penalties in order to pay for the repair.