At least for mitsubishi, if you get an aftermarket timing belt, don't expect it to last much longer than the service interval which is 60K miles. But if you buy OEM, I've seen them last well over 100K miles despite the 60K service interval. Just buy discounted OEM parts online, price should be close enough to aftermarket in store prices.
I buy aftermarket accessory belts though as it usually doesn't matter if they fail, so long as they don't get wrapped up around something and break something in the process of them failing.