Like many here, I really baby my equipment. I do it because it's my nature and also there's always the thought in the back of my mind - "What if I want to sell?"
I wanted to get cases for my immaculate 70-200 f2.8 IS and my 300mm f4 for two reasons really....one, so I can keep the original cases pristine and also as expensive as they are from Canon, they really don't offer much protection. Literally no padding at all.
I know that companies like Tamrac and Tamron and Lowepro make nice cases, but since I read different reviews on places like Amazon, (the liens fits, the lens doesn't fit, the lens fits, but too tightly, etc.), and I like to see what I buy when it's not something I have 100% certainly will work (rather than hassle with returns and/or exchanges), I ended up buying some used cases at the last of the "mom and pop" camera stores in my area (great store, huge selection, but high prices...plus tax).
I found cases for those two large lenses and a smaller lens used. They were cheap enough, but not perfect. They do the job, but the shorter Tamrac case I got for the zoom is too tight to hold the lens with the tripod ring,...not a big deal, but it would be more convenient if it did. The longer and larger Tamron case I got for the prime lens has room for the ring, but isn't padded toward the top. Just thin nylon with a cinch cord to close the case.
For me neither issue is a big deal, but today I found the perfect size case for both lenses - $19 each...fully padded and the right amount of room for the lenses with the tripod rings attached (or not)...
Oh....also the Canon cases, while they do fit the lenses with the tripod rings on them really are too small with the Arca/Swiss plates I have on each of those lenses.....I can force the zipper up, but the velcro attachment at the top is tenuous at best, and I'm sure over time if I used kept the lenses in the cases with the A/S plates attached (they are on VERY tightly), the cases would lose their shape, or I'd break the zippers eventually.
Anyway, the cases I found at Walgreens are labelled as cases for small portable oxygen tanks....so I guess since Case Logic knows that people with big expensive lenses spend more loosely than people more likely to be living on fixed incomes and medical insurance, apparently priced the cases well below their (possibly same) cases that are "lens specific".
The cases come both with removable clip on straps (same style as the Canon cases, but wider) and with belt loops (adjustable with Velcro like most lens cases).
Thought it was a good deal...no advertising "Canon" or "Nikon", just a plain black padded case that closes completely.
Hope this is useful to someone besides me! LOL 
My Canon cases are safely stored in their original boxes, so I'm a happy anal-retentive! 
Peace,
D.
