If it’s your first cosplay, start with something easy that you like and choose characters that have a similar body to yours, so your cosplay becomes more similar to the character.
I usually buy at these stores, Are shops with very good prices:
Wigs and accessories: http://www.wig-supplier.com/
Contact Lenses: http://www.uniqso.com/
Good luck on your first cosplay! =^-^=