First Time Home Buyer in Need of roofing thoughts
You can get an estimate if you contact a company who specializes in flat roofing work and inform them that you would be willing to pay for the estimate as an inspection fee.
Many companies will then charge the fee for the estimate, which is reasonable since you do not actually even own the property, and then credit you that amount or a portion of the amount charged once you decide to have them proceed to do the project.
You may also have to get written permission from the current owners to have a contractor come out to the property and do a proper, non-destructive analysis, waiver agreement.
It would be money well spent, but the current home owners do not seem to be misleading you, so why do you expect them to pay for a new roof for your enjoyment when the current one has served them well?
Only if there were signs of existing leakage, would I view it as a major concern, and then still, wouldn't you be expected to own the home and provide your own proper maintenance for aging components?