in my experience, there will not be a lot of spokes at the swap meet. i'm not saying there won't be some there, but i've been to this swap meet the past 3 years, as well as others, and it doesn't seem to be a popular item

i will be at stop swap & save with velocipede (a bike co-op in baltimore). we will have a table, and if you would like, i will bring you a handful of 306mm spokes you can have (like, for free). we have been blessed with a huge influx of parts donations over the years and have a large excess of spokes for 27" wheels. even if you buy a whole new bike, you can at least repair that wheel to resell or keep as a secondary bike!