Well-built cables that total to less than ten percent (mine are about five percent) of total system cost is a fair figure for cable cost
I believe that most people's cable costs generally work themselves out to be around 10% of their system costs anyways +/- a few percentages. When I first bought better cables, they represented more than 10%, but as my components improved, the ratio has fallen back in line. When you think about it. 5-10% of $10K is $500-1000 of $30K is $1500-3000 of $50K is 2500-5000 and of $100K is $5000-10000.
When you tell someone you spend thousands on cable it might sound outrageous and not worth it, but if you think about your cable costs in relation to your system costs, I think it appears more reasonable than the dollar figure for most people. After all, how big of a difference is 2-3%? Would you normally go into a store because they're advertising a 2-3% sale on all merchandise? In dollar terms though, it can be quite a bit of money.