Utah, in my experience, dealers hire these "factory reps" and pay them a commission just like they pay someone from their showroom. These salespeople generally have a higher closing ratio and do very well at shows. Also, most dealers don't have enough salespeople to cover the fair (or other event) and the showroom at the same time. These people usually work for many different dealers all over the US.
If there's a special price at the fair, I'm positive the showroom would be offering the same sale if you'd like to buy it from the guy you spoke with previously. If you liked the Fair person better, buy it from them.
You'll be supporting the local dealer either way, but if you buy it at the show, the normal showroom sales guy wont get anything for his time he spent with you a month ago. Generally. This is all from my experience, so I'm not saying it's the way all dealers work their events and with their show teams.
Good luck with your spa shopping!