With the 0 and 9 being close together on a keyboard, one would assume you made a typo and ment 3900 instead of 3000. However, the 3900 (which is an awesome moving platter media-player btw) is hardly “old” Denon gear. So, you would be talking about it’s original pre-predecessor, the actual DN-S3000. As with all Denon gear, build quality will be great, making buying used gear just a little less scary. It has plenty of functionality, but for example only has 1 hot cue if I am not mistaken.
Something else to take into account is that it is, obviously, an active (moving) platter unit. It’s really nice, if you have used turntables in the past. If not, I know DJ’s that came from CDJ-type players with static platters that really never could get used to active platters.
If you are in Europe, you might consider getting the Denon SC2900’s. Static platter like your currently players and that is where the comparison ends. They are currently priced ridiculously low, it’s truely a steal, considering you get a player that feature-wise is generally conceived to be between the CDJ-900 and CDJ-2000, with a build quality I personally would say is better than both of those players. Price is now just under 400 GBP or 475 Euro.
I own a pair (and paid quite a bit more for them) and they are absolutely wonderful units.
Hope that helps.
Greetinx.