Not everybody has access to a sewing machine, or the time and energy to sew. Luckily, the internet is full of sites catering to Rennies. Many costumes for sale on these sites aren’t fully historically accurate, but it’s still doable to pull something together from them that meets the SCA’s “looks authentic from 10 feet” rule. Just avoid crushed velvet, leather bodices, and anything labelled fantasy or gothic.
First of all, if you want to support small artisans and the RenFaire costumer community, take a look at Etsy! Many artists and sewists will do custom work, and you can often negotiate a very historically accurate costume. The downside is that custom work takes time, and the costs are often higher. After all, you’re paying for the time of a devoted first-world sewer instead of an underpaid worker in southeast Asia. Some of the more reasonably priced and historically accurate Etsy shops I’ve seen are Faire Attire and Well Dressed Lady. If you can’t afford to buy a full costume from an artist on Etsy, it’s also a great source for accessories. Check out Folk of the Wood for bags!
Next are the conventional commercial offerings.
If you’re really on a budget, try Tudor Dressing. The costumes are the cheapest I’ve seen, but may sacrifice quality.
One step up is Pearson’s Rennaisance. They have a larger variety, similar or slightly higher prices than Tudor Dressing, and the quality is higher.
RenStore is another good source, pretty similar to Pearson’s Rennaisance but with a somwhat smaller stock and fewer “fantasy” options. They have some cute, historically inaccurate brocade bodices if you’re into that kind of thing.
FantasyLand Costumes has a nice Renaissance section, with the Lady and the Fool line of bodices and costumes. It’s a good source for accessories as well, but it’s easy to stumble out of the Ren section and end up in back in Stretch-velvet Princess Land. Prices can be higher than the other three commercial options, but are a good value for the kind of product.