Why Do Thai People Always Talk About Money?

My predicament is how to answer ? If I tell them the cost (like for my bike) they roll their eyes and give me the ''crazy farang look'' or they think I'm bullshitting them.. Or I mumble something and freign memory loss and they still think I'm a dumb farang.. lastly I can tell them in Thai that, ''It's none of your business'' which can sound offensive or tell them that they are being nosey (which is deffo insulting) None of these seem to be good solutions especially the latter..

I've hit on a few pretty good responses:

"How much did you pay for that?" -- "Too much!"

"How much money do you make? -- "Never enough!"

Both said with a smile and twinkle in your eye. Never offended a Thai, but they get the point that it's personal to me.