If you travel a lot, you can say a friend has offered their frequent flyer points to you to get free flights or that you have a friend working for an airline who gets dirt-cheap flights (both have happened to me in real life, so it's possible).
If people make comments about my expensive phone, laptop etc. I tell them that before I bought it, I used the same old cheap phone/laptop for years, so it's not like I'm always spending tons of money on that sort of stuff. Or say that you're paying for things in small monthly installments.
In general it amazes me how many people, even new acquaintances, make remarks about other people's apparent wealth/money situation. Unless it's your good friends or family wondering what's going on, I think it's really nosy and impolite, and I do have a tendency to say so to people I barely know who are snooping around, trying to figure out whether I'm well-off...