There are regular trade shows, conferences and events in USA nationwide. There are conferences and trade shows are available for every interest you can think of. Pick those trades shows which you think, your target market segment for your Custom Feather Flags would participate.
There are good chance you could make a fortune, just if you could find one or two volume buyer for your feather banners custom printed in their graphic. I noticed that there is an California boy exhibiting in all the car shows are living very well in selling his outdoor advertising signs.
Nowadays, basically all business needs a website, or better to be a full e-commerce online shop. However, just setting up the website would not generate any sales automatically. You need online advertising for your custom feather flags on search engines to generate traffic and leads to your custom feather flags digital shop (e.g. one-economy.com). You can easily find more information regarding this, on any major search engines.
It may be expensive to design, produce and maintain your website, because there is no doubt that there will be a lot of updates to be done, unless you want to keep ransoming, I suggest you do it yourself. There are a lot of cheap online shopping cart solutions (e.g. godaddy), which you could consider for your custom feather flag online shop.
Besides the ppc search engine ads, you can explore the opportunities to get some free online ads on blogs which they might be interested in writing articles on your custom feather flags. Doing so will increase your ranking of your organic search results also.
Make a free youtube video for your custom feather flags! You could easily do this simply with your cell phone, with just some simple video editing apps. The video can be incorporated into your website, thus increasing your search rating even larger.