I bought a couple of used ones on eBay a few months back. Very cheap. Just don't buy the first two models as TiVo won't activate them to an account. I found out the hard way.

The minis seem to last forever, so buying used is the way to go or I guess the only way to go now.
By "first two models", are you talking about the A92 and A93 TiVo Mini or something else? If so, that's worrisome. I was able to get the A92 units (below) onto my account but this is awhile ago.
Not forever. There was a HUGE cluster of boot loop failures of the 92 and 93 series all close to the five year mark. Lots of posts here on MANY dying. I had four 93's, lost two within weeks of each other, both about five years old. Sold the two that still worked, moved to the MiniLux.
Still have four MiniLux going strong.
Bummer. Yeah, of course I'd heard about the failures eventually. My A93 mini that I bought new and activate at end of April 2017 still works fine. Eventually, I put 120 mm fan on top to suck the air out more quickly and keep the temps down.
Because of my worry about failures, I started looking for used A93 or A92 as spares. I was only able to get A92, one from a guy at work and another from a TCFer. The TCFer one still works fine and I use it almost every day when it's hot out (it's downstairs). My A93 is in my bedroom upstairs.
The other A92 from guy at work is currently unplugged. It has developed intermittent boot problems where if it fails to boot completely, I have to try again.
In colder months when I don't need to work a computer downstairs, the A92 units sit unplugged from power for a very long time (e.g. weeks or months at a time).
A93 gets powered up pretty much every day.
I turn off power (via surge protector) to the A93 when I leave home and the A92 (if I used it at all) when I leave home or go to sleep. A92 also has a 120 mm fan on top to pull the hot air out.
As for dying, who knows what the cause is? Is it because some component(s) tend to fail due to old age or a certain # of hours of operation? Heat? Flash memory gets worn out from too much writing?
I think I have enough spares for now as they will all become almost useless when Comcast finally pulls the plug on CableCARD in my area. I can't get OTA reception worth beans here.
Maybe if one unit dies, I'll look for another spare, assuming they can be added to my account.
I dunno about that. You got what is essentially a TiVo with most of the functions (except multi-tuner) in a very small and silent (no disk spinning) package with lifetime service for less than $200. Very convenient.
To me, it's expensive. Look at the price of
Roku. Cheapest 4K unit is $30. Yes, their business model is different. They get revenue/support via a bunch of sources.
TiVo's blowing out Edges for $25 + $250 for all-in plan.