I don't know about this one but sometimes the numbers aren't as important as the quality of the targets that show up. If those were people that could have funneled you work, forty could have been plenty. Home shows have lots of numbers but it doesn't always equate to actual buyers.
Wells Fargo did one here and their numbers were low 40-50 but those attending were people we are trying to reach. Realtors, home inspectors, or service professionals. It was a nice small show. The home shows we do, cost as you mentioned $1,600.00 and you see a lot more people. Many more people but some are building new homes or are out of the service area or are remodeling DIY'ers, not all are potential clients for cleaning.
We do both small and big shows, I think both can work well if you put the time into them.