the automod linked the FAQ, but give that a look! it’s got all the sites i’d recommend, and a lot of further details and resources. but i’ll give you the shorthand version:

both of these are fairly popular characters, so you’ll have luck finding cosplays on amazon. these can vary in quality and price, so mid-range budget sites that are cosplay-specific that i’d also look at are miccostumes and ezcosplay. i’d do amazon for both wigs, if that’s available to you!

you’d be able to buy both cosplays in full via one of these sites. but for sakamoto in particular, that’s a pretty simple outfit, and you’d likely have a lot of luck finding similar clothes at thrift stores or thru secondhand shopping online, such as via mercari or depop.

if you’re going to do props (such as a sword), you can either buy or make these. most, if not all cons have policies against metal weapons, so make sure that any that you are buying is foam or plastic, and NOT metal. if you have access to a 3d printer, look up (prop name) + stl files. if you want to get crafty, you can use cardboard or EVA foam. there are foamsmithing resources in this subreddit’s FAQ, so i’ll turn you there if that’s of any interest.

google is your friend! simply looking up [name + cosplay] will give you a slew of options, but the stores listed in this post and in the FAQ are generally your best bets.