Costume shops may be best suited to a bit of preliminary research and trying on of clothes. Since their clothes are most often rented for parties and to casual wearers, check the condition of the clothing very carefully. If it is simply a problem of cleanliness, most reputable stores will clean the costume at your request. If you plan to rent a costume from them, be sure to ask if they have different rental policies for the month of October. We're still three weeks away from Hallowe'en, but that may be close enough for some shops to treat it differently.
Local phonebooks or theatrically-inclined friends can usually point you toward the theatres in question. Who you will want to speak with will vary with the size of the theatre, certainly; who ever you speak with, be sure to be very clear about the duration of the potential loan, and your willingness to comply with their requirements. Sadly, some theatres have had bad luck with loaning costumes, and it may have made them leery of doing it again.
Happily, if you are working directly with the costume mistress/master, you will have the chance to speak with someone who works not only with costuming, but with actors, training them to move correctly and easily within unfamiliar clothes. If you decide to wear something quite different from your everyday clothes, this knowledge can be very useful!
Shakespeare is a mainstay of many theatres closely tied to academia, and although productions are not infrequently in some innovative design, there are still quite a few productions that are put on in full Elizabethan regalia. If you want to wear something in a late Renaissance style, you may find some excellent options here. In addition, pirates populate many a Gilbert and Sullivan stage, and wenches, nobles, and peasants fill out the casts of revels and madrigal feasts.
As with a community theatre, you will want to be quite clear about your intents. Some departments will class their resources as college property, which usually carries quite strict restrictions on its use. Again, though, should you have a chance to work with the costume shop, you will be dealing with enthusiastic and well-informed people, who will be an excellent resource.
Below, I have listed contacts for the SCA groups local to many of your areas. Like the other resources in this list, I cannot guarantee that they will have garb to lend, but many groups maintain a closet of loaner garb so that new people can come to an event without having to spend a lot of time sewing first. Many of the SCA members are quite skilled in recreating clothing of their chosen time period; think of it as a chance to show off their skills.
The listings are in the following format: The name of the group is first; if they have a web page, I have included a link, in case you'd like to explore. The group's Seneschal (essentially the primary contact point) is listed next, with their persona name followed by their 20th-century, or "mundane," name. (Hence the format AEtheldreda of Tamworth, mundanely known as (mka) Molly Harbaugh.) Email addresses are listed if available, and postal and telephonic contact points.
Barony of Carolingia (Boston, MA)
The Seneschal is Lord Gideon Alexander, mka Charles Sumner
csmuner@fas.harvard.edu
(617) 629-4867
Shire of Iron Bog (Camden, NJ)
Barony of Red Spears (Toledo)
The Seneschal is Lord Erik Viligisl, mka Eric Naujock
erlic@aol.com
4000 Sylvania #107, Toledo, OH 43623
(419) 472-4452
Unicorn, March of Flaming Gryphon (Miami University, Oxford)
The Seneschal is Ian Farrar, mka Ian Baby
babyid@miavx1.muohio.edu
201 E. Chestnut St. #117, Oxford, OH 45056
(513) 524-4336
Shire of Starhaven (Brevard County)
The Seneschal is Lord Stephen Greyhawkes, mka Steve Pierce
stephen@greyhawkes.com
901 Pine Baugh Street, Rockledge, FL 32955
(407) 636-2930 until 11pm
If you have any questions about this pages or the materials contained therein, please contact Carla Emmons, my most gracious maid of honour.