Not sure how keen I'd be on stepping into a tent to watch a slide show at a farmer's market. Too many people, takes too long, may be hot, can't see or hear well, etc. I think I'd be more attracted to a photo display with short captions and maybe a pamphlet to pick up (all doable and inexpensive with photo print paper & simple desktop publishing software). Maybe even have the same photo on display at the farm's booth that is in the main display to visually match them up. The slide show already created is not lost, just repurposed. IMO, I rather like the low-tech atmosphere at farmers' markets.