The scare stories are all to do with ready-mades, though I would think that failures are less than most other hi-tech components, there's not much within apart from a conventional HD
The cheapest and obvious way if you have a spare hard disk is to buy an enclosure.
Whether self powered or not is your choice depending on how much you need to cart the thing around.
Having bought just such a gadget this week from my favourite suppliers I notice that suitable enclosures for IDE drives are almost not existant now, the market has gone right over to SATA the reverse of what it was only a few months ago.
This may influence your choice of enclosure, SATA long term or IDE to use HDs you already have.