The letter IDE in an IDE hard drive stand for Integrated Drive Electronics. Most computers today have an EIDE hard drive, which stands for Enhanced Integrated Device Electronics.
The integral digital electronics (IDE) hard driver device is the most popular way to connect to the computer. It can be purchased through Amazon or Best Buy.
There are a variety of stores which sell IDE hard drives, you can get the cheapest deal on eBay or Amazon, you may also get some used ones at more cheaper rates but it depends on what you want.