I will concede that’s a reasonable price depending on where you live for a non performance drive. In Canada that’s about $20.89 after tax assuming you’re not paying shipping with prime. Then if you don’t have a ssd enclosure add another $15.81 after tax assuming you have prime for shipping. I would recommend a ssd enclosure that doesn’t pull power from your routers usb power to reduce heat which might cost a little more. (SSD enclosure was a cheap one)
So that hits around $36 cad which still quite reasonable, but would you spend $36 when you have a bag of usb sticks a decent about of ram on the router and no swapping occurring on the sticks. Sure it will probably preform a bit better, but negligible at best. I’ve been running the same usb stick for 3 years with no issues with bad blocks. At best I’ve had issues when not unmounting the usb stick before updating the firmware which could cause issues with ext4 journaling, corrupting. But a stupidly easy fix if you are running really basic packages.