Where to Buy & Tutorials

Wigs

Arda
Color blending is nice, the classic wigs are a nightmare when it comes to tangles though their silky line has less of an issue (at the expense of them being a little shiny). A bit expensive but there's lots a fiber in there and they sell all sorts of wefts and clips. They also offer lacefront wigs however the hairline is very strange so expect to ventilate or add wefts to them. US and Canada based, decent shipping, occassional sales.

Epic
The fiber is very tangle resistant while not being super shiny. Main downsides are no lacefronts and most importantly no color mixing so it has a less natural look. Still my go to for long wigs. Recently added off the shelf clip in bangs and pigtail styled wigs. US based, fast shipping, good sales.

Assist
The widest range of colors out there, if they don't have it then it probably doesn't exist. They are a bit pricier and don't offer lacefronts but the wigs are soft and look nice. Japan based, EMS shipping so pretty fast but a little pricey.

Ebay
So you also like to live dangerously? Ebay is where you go for multicolor wigs or if you're willing to gamble on a wig because they are cheaper. I've had about a 50/50 success rate with ebay. My Sayla, Kirara and Liam wigs were great as were a blonde lacefront and gold/orange one. My Heroine, Serena and several others were either terrible and tangled super quick or super tiny (and not the best fiber). Sellers rotate pretty quickly and most of what were considered the reliable sellers have either moved on or aren't as good as billed. Also most of the cheap wigs are shipping from China directly so expect a month of transit time.

Fabric

Mood Fabric
If you need a plain but fine fabric like silks they are the place to go. They also have some interesting patterns like Liberty of London. Shipping is fast but prices are a bit high and very rarely are there coupons or sales.

Spandex World
The go to for your stretchy needs! Fast shipping, good prices. Their $6-8 rayon lycra is a little thin so plan to double up or go for the rayon/lycra at Joann Fabrics which is thicker.

Joann
The go to for plain fabrics or super small amounts. Not bad for apparel fabric. Lots of sales and coupons. Right now they have a really good vinyl/pleather in their apparel section that comes in red, burgundy and teal. Great for cotton prints as well.

Hancock
If one is still in business around you, it's a good place to go if you're looking for apparel fabric or special occassion fabric that Joann doesn't have.

Dharma Trading
Not just for paints! They also sell plain and a handful of colored fabric. The exciting part is that they have a hella variety of natural fibers so if you know your fabric names you can do pretty well. The fabric is cheap and shipping is great. They also sell monster sized swatch packs so if you want to learn about the differences in fabric that is a good way to do it!

Tandy
If you need leather this is the place to go! You can order online, by phone or in local stores. I mention by phone because if your local shop doesn't have a product or enough of a product they can find one that does and you can call that store and they'll ship it. Very handy when you need five pearl white sheep hides.

Ebay
The hail mary of fabric shopping, sometimes you'll find EXACTLY what you need for super cheap and other times it's all junk.

Custom printing

Spoonflower
Cheaper option, very easy to order from. The fabric and print quality are okay. Kinda slow.

Fabric on Demand
A much higher quality of print but the ordering process is a bit... antiquated. Worth every penny though, especially for stretch fabric.

Other/findings/tools

Ebay
Okay but for real when in doubt ebay. Esp good for buckles and other findings that you need a lot of.

Dharma
Fabric paints. This is where you get nice fabric paints and also leather paint.

Plastic Beads Wholesale
If you need wholesale amounts of cabochons, this is where you go.

Contacts

Pinky Paradise
Used to be good but got a very strange payment system. Contacts are still alright, just very shady ordering now

Honey Color
Go to, simple, easy, not bad prices.

Shoes

Either locally or from ebay tbh.

Drafting/Cloth:
Fabric Over Foam Costuming (RAM Gauntlet)
Basic Bodysuit Drafting

Hard Surfaces:
Worbla Finishing Methods: Overview

Wig related things:
Pin in Crown Braid (Diantha)

Make-up:
EDI's Make-up