MSRP on a new Suburban is $62,000 USD -- with no money down, you're looking at over $1,000/month.
Last year we considered getting a new Tacoma -- the model I looked at had MSRP $43,000, and these days there's still no dickering on price. With a trade in for my Camry, the monthly payment would be nearly $500.
I typically spend $300 to $800 per year in repairs on the truck, not including oil change and tires (I put < 2,000 miles per year on the truck, so the tires will dry rot before they wear out), so keeping the old one for what we need is a far better choice.