People about Cosplay...
No, it is perfectly normal to buy a cosplay costume. Even professional cosplayers buy or get the costume made from someone else. However, making your own costume has a different thrill to it.
What is important though, is how you carry the costume and how much fun you’re having while cosplaying.
As for “devaluing someone’s participation” goes, some may feel that your cosplay is superior to them, when they took more efforts. However, it is not supposed to be that way as these things are done for fun.
Pick your favorite character, or one you would have the most interest in creating, and start looking for items that can be turned into props. Go to the thrift stores and find clothing that can be altered, or may even work as it. Figure out how to do an ‘adaptation’ of a character – for instance, I have a Rarity (My Little Pony) costume that is a purple skirt, purple and white blouse, large white hat and purple wig. I have either white or purple heels to go with it, but I forget which. Everything except the wig was repurposed out of my own closet.
If you haven’t done any costuming at all before, pick a character that usually wears ‘street clothes’. There are also a ton of eBay sellers out there that offer custom made cosplays, but you have to be careful and read reviews about their sizing – a lot of them tend to run small. I’ve also bought stand alone pieces like corsets, boots, purses, etc., from eBay and Etsy. This one store on eBay sold cheap corsets for ten bucks each – they didn’t stand up to long term use, but they did work for about a year of conventions, each, and held up pretty good for the per-wear price. Anything you buy from a China eBay seller, plan to give it a month lead time. I usually get wigs and whatnot within 2-3 weeks, but the sellers usually say to allow for 30 days. And there are a lot of good inexpensive wigs on eBay too!
If you don’t sew, there are a lot of ways to get started, even if you aren’t crafty at all! those are skills you can pick up later on if you have a desire to.
Costume play is very powerful tool. Any role play, with or without costume, allows a person to express things with much less risk and responsibility. Through this self exploration proceeds unimpeded, and new behaviors are tested to see if they will be useful.
Constructively used, this allows becoming more oneself and testing of one’s environment and abilities. I allows a person to test revealing things about themselves and see if it meets with rejection, and extend their comfort zones. It allows testing of fears, e.g., permitting a shy person to try being outgoing to see how well it works for them.
On the other hand, a costume, role or disguise also permits a person to enact their worst and most damaging behaviors anonymously. It is far easier to behave badly if one has a costume or role which hides the identity of the person both literally and figuratively.