Two opposite aspects of this to consider. You'll have to acquire all the materials and tie at least one perfect example (with pictures or video to show the steps) before you can even advertise the "fly of the month".
1) Your business follows the above warnings, and you don't get enough interest to offset your overhead. Will you stop offering the previous month's fly each new month? Will you continue to offer it until supplies run out? What do you do with left over inventory? (If it's wrapped up in a legal business inventory, you'll need to look into the local business laws of using business supplies for personal use)
2) Your business succeeds and you start getting hundreds, thousands or more customers. Keeping up with orders will, definitely, eat up time. Inventory will take up space. Suppliers of materials might not be able to keep up with you.
E-mail them and ask how much time their "one man operation" takes.
Again, as I noted before. Good luck.