What can we do about my Dad's buying addiction?

We have TONS of old cars and trucks, nice ones i have to admit, that he’s been planning to fix up…But, he goes out and buys another one- and then he talks about getting rid of a nice car he’s already fixed up and LOVES to brag about and drive. Like last night, okay so he fixed me up a 1970 Mustang right? Well he goes it’s not worth ANYTHING compared to this Chevelle SS here. And i was like but Dad, ur not getting rid of my Mustang right? (We’ve had it for like three years now, and he put really hard work into it) and he said i’m gonna trade the Mustang for the Chevelle and i said no ur not, and he would not stop saying that and then he was like it looks like the Gto in my shop- u remember how crazy the guys went over that and i was like yeah i know, but they also love my Mustang and so do i. And then he said well, maybe i’ll just trade my red truck for it(that one is like a regular truck u would take to walmart and stuff and he wants to trade it) and he always has this look in his eyes like man look at that thing, it’s great! I’ve got to buy it!!! It scares me sometimes, and he kept saying look at more pics of it- more and i did and then i IMed my friend back on facebook and he was like what are you doing now? And i said nothing i was talking to Brent and he went ah damn and looked extremely disappointed like i came home pregnant or something and i went back on google images and he got excited- what’s his problem? It’s making my mom say she wants to leave him:(