Where to find the clothes?
Part of who you are will determine how you shall dress. Many times, I have had to portray various roles. Over time, I have acquired dresses for most occasions; starting out with simple, inexpensive dresses (portraying a mill worker or cook) to lavish ball gowns (lady of high social standing or dancer performing vintage dances). Either way, you can stay within budget fairly easily.
First off, if you sew you will save 50% of what us “pretzel fingered folk” have to spend on dresses. If you don’t know how, there are several ladies within the community that can help you get started.
If you know someone that sews and can help you make clothes that will also save you money too.
If neither of these is available to (which was my case), then you can start with fellow re-enactors that may have “hand me downs’. I have founds some lovely dresses that fit me to a tee this way! Your re-enacting family can also give you links to Civil War forums. There is almost always For Sale message boards where you can find all you need.
Also, there are many online resources like Etsy and Ebay where you can find clothes ready for you and cheap.
Other resources for everything from boots to bonnets are SUTLERS! These are people who either attend events or have online websites selling period goods.
Do be aware there are many sutlers that say they sell “authentic period costuming” that are as far from authentic as the moon is from earth! As you spend more time in the hobby, you will be able to tell the difference between what is authentic for reenacting and what is not. Look at the list on the Links pages. These are ones I use or have been told by the reenacting community are trustworthy.