Well, WD will sell you a drive with a 136-year MTBF right now. The entire RE series is listed as having a MTBF of 1.2 million hours, which if you do the math is about 136 years.
So there you go, buy one of those. The warranty is only 1/7 of your request, and the price is a little cheaper, but hey, you're in business.
In reality, of course, MTBF does not correlate to real-world lifespan in real-world use, since by necessity it's determined through accelerated testing. But at least in as much as accelerated test methods allow, you can buy a 100-year drive today. Of course, even if that were correct, the chances of any other component in the computer using it surviving even 1/10 that long are pretty slim. I expect were you to be able to buy a computer that'd last 35 years today it's unlikely you'd actually want to use it in 35 years. Not that growth hasn't leveled off somewhat, but I don't see many 1985-era computers in use today, and I can buy a phone roughly comparable to a 10-year-old desktop now.
Actually, if you go buy one of the Sandforce-based SSDs from OWC, they have a 10 million hour MTBF, which is 1141 years. Which, if true, would mean that had such drives been available in the middle ages, half of the drives manufactured in the year 868 would still be running. Which would be cool, but I'm skeptical you'd want to use a millennium-old computer.