Alright, I'll join in from the fantasy pirate perspective :)
1. Boots: the most expensive part, but I agree with others that they're the hardest to borrow. Now if you're lucky you might even find relatively cheap boots too. I once found a pair for € 50 in a high street shoe store so just look in every shoe shop first, you might get lucky :)
2. Skirt/trousers/breeches, whichever strikes your fancy. If you're doing fantasy pirate then you might as well wear pants as a girl :)
3. Pirate shirt: I'm sure the other ladies will agree with me that going topless is not a good idea
4. coat
5: tricorn hat
6: flintlocks
7: sword (in my case it's a LARP cutlass, as I take it larping ^^)
8: waistcoat . I've put this on number 8, because personally, if you're doing fantasy and you've got everything up to number 5, then it's quite obvious you're costuming as/portraying a pirate already ^^
Although if it's warm and you're starting out, it might be wise to get the waistcoat before the coat as to not bake to death from the heat
9: food, drinking and camping gear
10: every other bit you feel your pirate persona should need