default to high price rather than zero

src/ship/shops/armor.rs

@@ -38,7 +38,7 @@ impl ShopItem for ShopArmor {
                         price += 70.0 * frame_stats.level_req as f32 * *slot as f32;
                         price as usize
                     })
-                    .unwrap_or(0)
+                    .unwrap_or(0xFFFF)
             },
             ShopArmor::Barrier(barrier) => {
                 SHIELD_STATS.get(&barrier)
@@ -49,14 +49,14 @@ impl ShopItem for ShopArmor {
                         price += 70.0 * barrier_stats.level_req as f32;
                         price as usize
                     })
-                    .unwrap_or(0)
+                    .unwrap_or(0xFFFF)
             },
             ShopArmor::Unit(unit) => {
                 UNIT_STATS.get(&unit)
                     .map(|unit_stats| {
                         (unit_stats.stars as f32 * UNIT_MULTIPLIER) as usize
                     })
-                    .unwrap_or(0)
+                    .unwrap_or(0xFFFF)
             }
         }
     }