Considering how many new players will (hopefully) frequent these forums, and how many of us might want to introduce some fresh pieces into ongoing character costumes, I thought it would be fun to share some of our favourite shops and costume makers!
Please include whether it is a budget, mid range, or luxury vendor. While this might be pretty subjective, I'd call budget pieces 30-40 dollars or under, mid range as 40-80 dollars, and luxury as anything where you'd be braced to pay upwards of 90-100 dollars or higher for a single piece or simple set. I'll answer this question with some of my own favourites as an example.
Note that I intend for this to be base costumes specifically, not armour. Feel free to include vendors that provide both, but the focus should be on "clothing" and accessories!
He/Him. Transmasc in progress, please disregard mine bræsts.
Ralinwood: Ketilmundr Halfgrin - Einher, Mystic and Vitki, Chaos Enthusiast
Jericho: Tierney Oisin - Wild Elf, Apothecary and Druid, Friend to the Fae
Retired: Carrion - Human, Priest of the Nightkeeper, Ambassador for the Dark
As we get started I of course want to make it clear that more expensive does not always equal better. I know people who have managed to thrift entire looks, and my own costumes have included pieces in them that ranged from ten dollars to almost two hundred side by side. Larp is a hobby, as is the costuming element, and one should not feel obligated to spend more money than they're comfortable with. For me, costuming is most of the reason I larp and an excuse to wear nice clothes I can't in every day life, so my tastes do skew to the expensive side. Hopefully this thread will show, however, that there's so many options when it comes to building a look for your PCs.
While I spend a lot of time combing etsy or niche fashion companies for appropriate pieces (my dark cleric's costume was 50% Punk Rave pieces towards the end) here are some more medieval/larp specific favourites of mine to get us started. I won't be mentioning Epic Armoury or Calimacil because I feel like they're so well known that there's not much point, and also because I haven't actually gotten much costuming from them and thus cannot speak from experience. While there are other sites I am eager to try and may be able to recommend at a later date, I have only included the ones I have personally ordered from and tried or else seen first hand on a friend.
For budget pieces I am fond of Zootzu Garb.
They have provided both me and my partner with some very affordable and good quality pieces, and are particularly good for finding an inexpensive but durable under layer such as a shirt, vest, or pants you want to add more layers and accessories to. They also have a very wide range of sizes, though their men's styles are more forgiving (XXS-4XL vs the XS-XL). However, I find the styles intended for a more masculine look fit just fine on people with more feminine body types, so I encourage anyone interested to take a look.
I should really include something in the mid range (though a few options go into the luxury range), so I'll link Larp Fashion, since I think it's one of the more lesser known sites despite their extensive stock.
https://www.larp-fashion.co.uk/
Like Calimacil and other sites of its kind, Larp Fashion is a retailer for a number of distributors, and it has (in my opinion) a wider range of costuming options due to its access to UK artisans. They also have a number of "set" options where they've gathered pieces to make character specific looks you can either buy as a full kit or browse for inspiration.
For for luxury pieces I will of course always shill for Armstreet.
They make some of the most beautiful costumes I've ever seen, including in custom sizes and in a wide range of colours, fabrics, and styles. They can be a difficult store to recommend to those who aren't as comfortable paying a higher price for their pieces, but given how affordable some become during their frequent yearly sales, I recommend checking them out or bookmarking a few favourites.
Also in the luxury range is Chow's Emporium.
https://www.chowsemporium.co.uk/ and https://www.etsy.com/ca/shop/ChowsEmporium
To me, costume pieces from Chow's Emporium strike a nice balance between costume and clothing. The fabrics are heavy and textured, the colours are muted, and they are very good for layering if you can bring yourself to shill out for multiple pieces. For people looking for a more rustic aesthetic to their costuming, I'd recommend them.
Value Village, baby! Very budget, and really contains anything you need except cloaks (though it does have shawls and blankets which you can make into a cloak, so really it's got everything).