i've recently decided i'm quite happy that i've gone back into full time work after years of freelance circus. Now I have salary so those horrible mid year months don't worry me too much though i'm saving to move to san francisco so i guess i can't actually spend any of it!
Beatrix and I were talking about this on Sat night. I do a spreadsheet too, worked in an entertainment agency so i know how important it is to keep track. I remember an artist coming to me six months after a gig claiming i hadnt paid him any money. Was poop it had just been spent before it went into his bank... silly boy...
don't worry too much, you will have times when you have spare cash for costume just budget carefully. Not every 'bargain' on ebay should be bought; choose your costumes with great detail and hunt to order. Wait for summer sales too, i got my fans buy one get one free and most of my corsets are half price.
Its also worthwhile contacting your local college and seeing if someone wants to use your act in a project? I had a dress made for me a while back by doing this, amazing for aerial work but sadly not burlesque.
Plus always remember the power of dead man's pants. My beautiful black taffeta dress (that ripped at the MOB awards damn you fifties zips damn you) was charity shop and until it split was worn with pride and lots of comments
good luck
vicxx