Hi there, fellow cosplayers. I'm a cosplayer, waist trainer (I use corsets to achieve a smaller waist), and all around corset fanatic. My sister is a fashion designer that has shown me how to construct a proper corset and I've been researching them and wearing them for about 2 years now.
I've noticed there's a lot of false information, misconceptions, and generally dangerous recommendations floating around on these threads so I'd like to clear the air.
First off, The Corset Authority
is your best friend. Not only are the people who run that blog super lovely, but they know a lot about buying and constructing corsets. On the sidebar you will find links to Bad Brands, Brands to buy from, FAQ's, and a lot more useful information.
I'd like to address buying from Corset Story/Corsets UK. As affordable and awesomely designed as these corsets are, not only are they incredibly uncomfortable (authentic corsets are not) but are also extremely dangerous as the boning could break as it is usually plastic, and not steel like they advertise. If it is steel boning, it's very crappy and cheap steel boning. I would never recommend paying less than 60 dollars for a corset, because the cheapest authentic corset seller I know of is Orchard Corset. They make lovely corsets in Satin, Cotton, Brocade, and Leather in a multitude of colors. Sadly they don't have Steampunk designs yet, but it's easy to sew on buttons, patches, and gears to these corsets to mod them to your Steampunk desires.
In short, I know not all of us have the money to buy an authentic corset, but when it comes to paying 40-50 extra dollars for a well made corset that's going to last you, it's well worth it.
Note, I am not claiming to be a corset expert, but if you have any questions I will do my best to give you a clear and concise answer.