On Rt 30 & 15 at Gettysburg is a Sleep Inn and Windham. Windham has really big suites with a huge walk in shower. $140 the last time we stayed there. These places are about 15-20 minutes (south on 15) from Latimore Fairgrounds.
If you're coming in from Pittsburgh there's a Hampton Inn on 15 South of I-76 on your way to the fairggrounds. It's about a 20 minute drive from there to the show.
staying at the Comfort Inn, at 15 and Tpke., ID'd as the Harrisburg West/Mechanicsbug Corporate Center -
The following accommodation information is listed on KOA. Mention KOA Car Show Hotels: 1863 Inn of Gettysburg 717-334-6211 Days Inn Gettysburg 717-334-0030 Blue Sky Motel 717-677-7736 Quality Inn 717-334-3141 Motel 6-$80 per night 717-334-4274 EconoLodge-$99 per night 717-334-4208 Super 8-$99&up per night 717-337-1400 Comfort Inn-$107&up per night 717-337-2400