Not common i dont think... most people who spend big bucks on cables have spent bigger bucks on the equipment... General rule of thumb is cable budget should be about 10% of your entire system...
That said, if somebody has a high end system, and bought a spare DVD player or to experiment with and had some spare high end cable lying around then that would be a reason to have a $100 cable with a cheaper DVD player
TV+AVR+SPKR=4K X .1= 400 BUCKS. That sounds just about wharer I am at with the cables. I went high end ov video and dig cables....low end on the rest. The DVD was a quick cheapie I needed ...and it is my first DVD. My point of course is to justify getting a better DVD...... LOL! It is a hard choice ....the prices are dropping on this stuff it seems daily if not hourly.
Don't mean to be insulting, but you alluded to it in your question. Yes, it is absurd to spend 100 dollars on cabling for a cheap 100 dollar DVD player, IMO. Cables, while they will have an impact on the performance if they are total crap, should not have to cost much.
I spent about $130 on 30 feet of professional belden RGBhv cabling, and you can't really do better than that. However, I am feeding a projector that cost at least ten times that much when new, via an HTPC with very high quality performance. (edit: apparently I can't do basic math, since 10x $130 is just 1,300. Lol. I meant 100x, another zero was necessary . )
That you spent 100 dollars for probably a short length of what is probably just component video cables, tells me you were very much ripped off.
To me, the "10% rule" is just a guide for the maximum you should spend. Even if you "only" spend 10% of your budget on cables, it's very possible that you still spent way too much on cable and wires.