I have a different approach to buying into a used CDP / CDT.
I look upon the Laser as a 'Sacrificial Part' that will one day not perform to the standard it was able to when new.
Being relatively new to a CD Digital Source used in my system ( approx' since 2016) all other recorded music replays has been produced from the use of a Vinyl LP. Where the Vinyl LP has been solely in use and now used in conjunction with CD for near 35 + years, which is the timeline for my expressing an interest in a Audio System, as being of importance.
This experience with using Vinyl LP's as the Source. Creates the conditioning for myself to be totally conditioned to buy into vital parts for the replay of Vinyl that are sacrificial in their function, i.e, most obviously the Phono Cartridge.
Being investigative as an involvement with Audio Equipment, where time is taken for communicating with / or meeting with others with a interest in Audio Equipment, will enable others with much more information on board than ones own to reveal information that is pertinent to achieving improved experiences when using Audio Equipment. When being social and being engaged in discussions on Audio Equipment. It does not take long to learn there are many items which are used to produce a Sound from a recording that are by their nature 'Sacrificial', there is a limited period they function at their designs optimisation.
Without going too off topic, the Phono Cartridge and Laser both produce the Source Information to be Transferred through the Audio Systems electronic design, to become an increased in gain signal, to the point the Voltage produced, is quite cables of making a Speaker produce Kinetic Energy, that is perceived as sound.
Both the Phono Cartridge and Laser are sacrificial, they deteriorate over time, to the point they do not function optimally to their initial design.
A Laser is expected to have much more Longevity of usage than a Phono Cartridge if both are being used continuously.
I am very willing to buy both a Phono Cartridge and a device that contains a Laser to read CD as used items.
In advance of a used item purchase, I do my research and learn what can be done with a model being purchased as used, when a malfunction is detected to be occurring. This is important to understand, knowing what are the options for a repair, if failure of the device is to occur.
There is endless information about successful refurbishments of Phono Cartridges, there is a Industry dedicated to offering such a service.
CDP - CDT is not met with such a easy to access support. Which does mean there is limited information to be found for a broad range of CDP - CDT models.
The good news is that there are CDP - CDT models that are being refurbished with new or alternative laser's (in some cases the alternative laser is much improved as a model over the original laser used).
A selection of these CDP - CDT models can even be discovered to have undergone additional design changes, that have added even more benefits to the electronic function of the device.
I bought into a used CDT that has been well documented and reported on as being a removed from being a repair item by the OEM. It is also well documented and reported on, that this same model has been successfully repaired by non OEM EE Technicians or even enthusiast Technicians when the Laser has failed. My own stand, is the CDT is purchased as Sacrificial, with the notion, there is plenty now known to make sure it has options to be selected as means to be repaired when that time arrives.
Used models of CDP - CDT can be found for approx' 30% - 50% of original retail when a prudent search is carried out.
My own CDT was bought for 40% of the original retail price. To date it has, as a Guestimate, between 1400 - 1800 hours usage. It is now used to reduce the use of a Phono Cartridge, which is even more beneficial.
The cost of CDT - cost of DAC, has been much less than that of the cost for a Phono Cartridge cost that is able to compare to it, when perceiving the qualities of each end sound that is produced. My CDT > DAC has been used in systems with a Vinyl Source Equipment costing £20K ish, with the Cart' being more than £3K. The listeners have been very vociferous in their appraisal for the Digital Source Equipment during the comparisons.
A refurb on a Cart' is usually anticipated at approx' 1000 hours of usage, but there is info from manufacturers that does not adhere to this guideline. Typically $450 and ascending in costs is a Cart' refurbishment quote, depending on the Cart's needs.
My used CDT has as stated, in my ownership had approx' 1500 hours usage. I am over the moon at that, as a longevity of non problematic function, the cost of usage into a hourly incremental breakdown, when compared to what can be attributed to a Cart' incremental hourly cost over a range of 1000 hours usage has the owned CDT coming in at quite a smaller cost per hour as well at this stage of usage.
If the CDT's Laser failed now. I can get the CDT back to functioning, by supplying the replacement part to a skilled EE Technician. The expected cost for both part and labour will be close to £100 +/- £30, if the professional service is the adopted method. I don't think l would be too far out in assuming another 3000 hours of Laser usage will follow. This starts to make the incremental hourly cost of a the CDT extremely attractive as a tool to generate a Signal, when compared to a hourly incremental cost related to certain models of Phono Cart'.
Add to the addition of the CDT > DAC the vast CD Collection now acquired, where a large range of CD's bought used has been for less than £1 and more expensive being between £1 and £5, the Music Collection able to be replayed has exponentially grown. I would be comfortable stating the cost of 10 x Typical Purchase Methods, used Vinyl Albums, has cost the same monies as more than 300 CD's being purchased.
From my end there is a substantial amount to like about the Used CD - CDP - CDT market.
Careful Purchase Planning and Caveat Emptor are ones best friend in such a matter.