Don't know if it's an indicator on that one , but the grousers , aka toe nails, are gone. Check and double check the undercarriage and idler rollers. That's where the big $ to repair is. If the undercarriage is worn but has some life left it'll run a long time just putting on the farm. Those 700s are good machines , great size too. Price depends on hours and undercarriage . Could be anywhere from 30K up. There's 0 chance I'd give 40k for a JD 700 with high hours and worn out undercarriage and tracks.

I'll suggest get someone who knows tracked equipment you trust to look it over.