Think of preventative equipment like UPS, RAID controllers, tape drives, etc. as insurance. If you're willing to risk the odds, then by all means don't get the equipment. Save a few bucks in the short term and pat yourself on the back. But like a car crash, if you value anything about the car, then insurance is worth it as life in and of itself is a gamble.
Weeks, months, maybe years from then, what do you think the odds of something going wrong? Multiply that by the amount of time needed to diagnose, repair, test whatever problem occurs.
If money is an issue, I can understand skimping here and there because of a lack of funds. But if money is fairly accessible and you consider your work/computer/data/files/whatever important, then not buying any preventative equipment is simply foolish.
To answer your questions directly:
Is it worth the money to invest in a
battery-backed UPS unit for a home
Do you consider your data valuable or not. If you do, then I would definitely spend the money. $140-$160 UPS goes more than a long way for a home computer. There are probably cheaper units that are just as effective. I'm not saying you have to spend that amount but there are a variety of brands available that might meet your needs.
Or is it a waste of money?
Prevention is seldom a waste of money. I've had numerous disks go bad in my lifetime. Then I tried software RAID. What a joke. I still had data loss. Then hardware RAID (no problems yet) and now NAS (network attached storage) with an attached UPS. I sleep very comfortably at night with well over 400GB of storage.
The purpose of the UPS would be to
prevent a "meltdown" of the computer
due to bad power in the area, i.e.
The general idea behind a UPS is uninteruppted power supply. If a brownout occurs, no problem. The UPS switches to the battery to supply clean power and switches back when the line is A-OK. You'd be amazed at how many brownouts/blackouts occur when you're at work or in the middle of the night. Make sure to use the software between the computer and the UPS to log issues that arise.
With the cost of some computers, the
UPS approaches half the replacement
cost of the machine, which is why I'm
Equipment costs aside, paying $300 for a computer and paying $150 for a UPS is a meaningless comparison. Let's be clear, data is the most important thing about a computer. When you get right down to the core, the difference between one machine and another is mere perception. If you could care less about files, and all you do is browse the internet, email and play games, maybe a UPS is a bit overkill. But if you value your personal and historical (private) information, a UPS is but a small step towards preventing disaster.
I should note there is one caveat to a UPS: cloud storage. If you care about your document/pics/whatever, you could use something like dropbox or Amazon S3 storage to remotely backup your information leaving your home computer to chance. Granted, if you trust those providers and wave any thoughts about your privacy, then that's a free/cheap alternative to a UPS.