I got the 300 disc case-it MC-300 from Buy.com first, for $28 originally because Meritline was sold out of the 500 disc case (plus I've had several shipping problems with Meritline in the past.)
Eventually I broke down and ordered Meritline's self-branded 500 disc case.
Here are my impressions:
Both of these items are obviously made by the same OEM but there is a fairly large quality differential.
The MC-300 has better fit and finish and is far more solid feeling and secure. I received it from Buy.com, a very reputable dealer along with a few other items in 3 days, with free shipping (may have been a special promotion at the time - don't remember.) Because the MC-300 is smaller, it's plastic panels are far better secured by the metal edges of the case. The hinges are smooth and well secured as well. The front of the case has a single latch with a lock that works well (not that it would keep a serious thief out, but its a minor deterrent for people peeking at your discs.)
The panels themselves are of a textured plastic that you dont even realize is plastic initially. Even if you do realize that they are plastic they will not seem cheap or flimsy.
The sleeves were already placed in the tracks and were fastened by a single plastic strip. Completely filled the box is still manageable in weight and portability.
I like the overall silver color and appearance.
The meritline case is larger (quite a bit larger) and the panels are much wider. I paid $50 for the case, and received it in about 10 days (UPS ground). The case panels are made from a striated black plastic that seems a little cheaper and flimsier than the MC-300 panels - maybe just because they are larger. Also because the panels are not as closely supported by the metal frame, I am more afriad this case will be damaged.
The hinges in the back were not capped(!) and this makes the lid become disengaged from the box just about every time I open it. A minor annoyance but just another sign of corners that were cut. The front is secured by two latches that do not lock, in case you care about that.
The sleeves were arranged in three plastic bags and had to be put on the rails which took a little while. These white sleeves are similar (except one is black and one is white) to the MC-300 sleeves but the black MC-300 sleeves look much nicer and less cheap somehow, IMO.
Completely filled this box is now quite heavy and not as portable as the 300 discer.
Overall, as you may guess, I find the 300 disc to be more practical, attractive and sturdy, and lockable, but the 500 disc case is still better than any of the CD binder wallet thingies.
Both are recommended. The cost / disc was about the same for me when I ordered them, but I'd pay slightly more for the MC-300.