Perhaps I read the post wrong. $800 for axles. My spare tire and rim to fit 7k axles ran $225 each, that's $900 for wheels. He will need a battery and break away switch. How good is his old deck? Does it need replaced? Did a certified welder put his trailer together? Does the old trailer track straight?
I sold my 15 year old 7k 16 ft utility trailer for $1200 and put another $2000 for a new one with no regrets.
The way I see it, he is looking at half the price, or more, of a new trailer to fix up the old trailer, not $60.
I would go with a new trailer if he wants to be on the road. Stay with the old trailer if he wants to use around the farm.