I saw skip going to one vendor. Hit ebay first, honestly. Also, members here are ALWAYS selling Indy stuff. I mean, A LOT of Indy stuff is for sale.
If you aren't in a hurry, you could have a budget costume by Halloween if you only get two pieces a month until then.
I recommend taking your TIME. Really read everything you can before you start buying. And if you don't care, DONT get the "real deal" stuff. Get the "close enough" pieces if you wanna save money.
Either way, post up photos of what you decide on. And if you REALLY want the best and want to spare NO expense, then Indy Magnoli is the best for the costume stuff. And his work is all unreal.
That's my two cents. Go for the budget stuff and hit the Junkyard for the sale stuff.
Good Luck!