I think having yard sales will be my primary market and the flea market secondary.
How many yard sales can you have a year? In my area it is 2 a year. If you are in a neighborhood where they don't care about the traffic, parking, people movement you could probably have more, but this is one reason I don't do yard sales...my neighbors wouldn't go for it.
I also live in a small cul-de-sac with a subsequently small front yard and driveway is in the back, so just doesn't work for me.
On the other hand the flea market is wide open, has a regular large crowd and has done well for me over the years, so am sticking with it. I pay by the month, but don't have to go if I don't want to, but so far the only time I miss is when I have a planned vacation and usually then, I only miss one Saturday by taking a 10 to 13 day vacaction. The only other time I miss is when it gets rained out, and I get a "rain day" credit for that 5 times a year which has always been enough.
The "rain day" has now been named a "vacation day" and again I can take up to five a year (total rain or vacation) and it has worked out well. One year we had 4 rain days in about two months, but that was unusually high.
Though everybody and his brother (almost) has an inflated idea of the value of "their" stuff, bargains are still found at garage/yard sales in my area. It's the "estate" sales that often have inflated prices.