With the current cost of building materials, it might cost you as much to build a decent, similar sized coop! I recently converted an old pasture run in shed to a decent coop with elevated floor, a cleanout area under the roost and added ventilation. It cost me double my estimate, priced in 2019, to do it in 2020-2021. (I move slower working these days!) I spent over $1,000 to convert the old 10ft x10ft building along with a similar size covered run, with some free hardware and fencing and lots of my time! You may spend more than you imagine on some improvements, alone. I gave away an old playhouse coop conversion about 5 years ago because it was too small for an adult to stand up in. It is worth a lot to me, to be able to easily clean and keep chickens safely and more comfortable. I got too old to put up with the difficult clean outs! Maybe, make a counter offer of $400 - $500 to help offset the moving cost and set up. Be sure to remember, to provide some mid day to sundown shade, at the least! Here in Tennessee(as you know) it gets tough on chickens in the summertime and a shaded house will be up to 10 to 20 degrees cooler inside. Good luck!