Actually, except for the personal attacks, what you say makes sense. If someone was selling a blade for 2x the price, you would expect to get 2x the life....simple.
The only place I disagree with you is that there is nothing better than an $80 blade. There is a middle ground, and if you could spend 50% more, and get say 60% more cuts, mathematically, that makes sense.
And actually the fact that many Hardscapers do NOT keep accurate track of things like linear footage, hurts 'diamond blade salesman', because they have nothing but feel to judge whether one blade performs better than another. Your attention to detail is what sets you apart from your competition, and helps in all other business aspects. Not everyone understands that...