Prebuys are getting hard to come by. A lot of shops are too busy for last minute work, and honestly, don’t want to be inserted into the middle of a deal that could go bad.
Last purchase I did, I paid to fly a guy into town, and made arrangements to have hangar space & jacks available.
That said, I’d try to focus on a shop that is an expert on your type. What’s good for a 182 might not be the best thing for a 210.