I tell the truth, then give the person an idea of the full range of bike prices.
People have such different feelings about talking about cost. Some people feel strongly that it's all private. At least at the bike level, I personally don't care and have no problem telling people what my bike cost, just as I've never minded telling people my housing costs. I know others feel very differently.
"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks