The highest capacity iPod you can buy today is the 128 GB iPod Touch for $399. Apple discontinued the “classic” iPod in 2014. You can still buy a new, last-generation iPod Classic on eBay, but it will cost you: over $400 at the time I’m writing this post.
Fortunately, there’s a way to get a high-capacity iPod for much less. Go back to eBay and find a used, good condition iPod 5th Generation (also called the iPod Video, since this was the first generation player with video playback capability). Prices for these devices are reasonable; I was able to pick up a good quality unit for around $50.
Next, head over to iFlash.xyz and pick up one of their iPod flash memory adapter boards. They offer several models with varying storage capacities; I bought the iFlash-Solo for $33. This board turns a regular (and cheap!) SD card into a replacement hard drive for your iPod, up to 128GB capacity. Other slightly more expensive versions of this board offer much higher capacities.
Directions for installing the iFlash card into your iPod are on the same page as the specific iFlash adapter card you’re interested in. You’ll need a “spudger” tool like this one from iFixit to pry apart the case halves on the iPod and be warned: you’ll also need some patience and time to open the case without damaging the easily scratched plastic face on the iPod. There are useful guides on YouTube for doing this. If you do damage the iPod, both halves of the case are available new on Amazon for very reasonable prices.
Also, while you’ve got your iPod open, you might want to replace the Li-Ion battery. These are available on Amazon for around $17, and include a plastic tool for opening the iPod case.
With this conversion, you’ll have a classic iPod with 128 GB (or much larger!) storage capacity, that is noticeably faster with a flash drive than the mechanical hard drive used in the original player. Even better: your new iPod is lighter without the hard drive and runs longer, too.