How do I pick between making or buying a cosplay?

When I'm picking costumes for upcoming events, conventions, etc. I ask myself a lot of questions before jumping in and starting a project. I know my time and money are valuable and limited while working a full-time job and maintaining my house. 

I try to stick to classics to make the most out of my time spent making the cosplay. I see nothing wrong with re-wearing a costume. I've found that while doing what is popular is fun, it is much less sustainable to keep up with trends. This is very hard when I see something new that I love the design of. 

What event I will wear the costume to plays a huge part in my decision. As a master's level cosplayer, if I plan to compete in the cosplay I am sewing at a higher level and adding more detail than I would if I were just hanging out at a convention. 

If I am a cosplay guest at a convention, I VERY likely made everything I'm wearing. I have worn store-bought before on a Sunday if I need something quick and easy. I determine this by costume availability and my physical ability to move in my cosplay. Fridays and Sundays, I'm setting up and packing up my space, so I can't easily wear long skirts or big sleeves. 

If I am teaching a workshop or hosting a panel on anything craftsmanship-related, I will have made my cosplay. If I am teaching, it has to be something I can easily move around the room in (no hoop skirts or big sleeves).

If I do a casual, fun, group cosplay with friends at a convention I'm just going to as an attendee, I will usually buy that to save myself some time. Same with some promo events if the focus isn't on craftsmanship and I need something new to fit a theme.

I am trying to limit what I buy to cosplay more ethically and sustainably. I love that cosplay has become more accessible to everyone, but I don't love the direction of fast fashion and its impact on the fashion industry and the environment.