a) SSDs are not designed for bulk storage. They will probably never match the $/GB of old HDs. If you want bulk storage, then put those bulky files on magnetic media (i.e. traditional hard drives).
b) Backups, backup, backups. Put a 2nd (or 3rd) magnetic HD on the system and use one (or both) as a target for an Acronis True Image Home backup each month. It's dirt-cheap at $30 (or the 3-pack for $75) and gives you a way to restore the customer's machine to a previous point in time. Even if the SSD dies, you are covered and can get back up and running quickly.
c) Most of the SSD sudden death issues are due to crappy controllers. Pay attention to reviews and avoid the bottom of the barrel SSDs. Image the SSD regularly so that you can restore the system to a new SSD when the existing one dies. Again backups, backups, backups.
SSDs just aren't that expensive any more. Prices are down in the $0.60 to $0.80 per GB range. If you can't afford that, then look into 10k RPM SATA for around $0.30/GB. Both choices are very good for your primary operating system drive and will goose up the responsiveness of an older system so that it can be used a few more years.
And if you're not willing to pay attention to the "backups, backups, backups" mantra, then you deserve to lose your data. Because it obviously wasn't important enough to you to back it up.