It really depends on what your looking for... If your wanting something with armor type plating you could use EVA foam cut and shaped to meet your needs. It is pretty cheap and can be purchased from most hardware stores in the form of those puzzle piece floor mats.
There are also some premade zentai suits you may be able to modify if your just looking for base to start from.
Robin Super Hero Costume Lycra Zentai Suit - Milanoo.com