Instead of using heavy duty card stock i used a thinner type, that was not as strong. once i had my piece cut out i would glue a piece of cardboard to the back and then once i had all my pieces i would assemble normally.
for the base coat of resin i did the normal steps, but after a thin coat or two I didn't do anymore. instead of using auto body filler for the outside, i used this Elmers wood past stuff that was hecka cheep and works really rather well.
Probably the place that i saved most was by not adding the fiberglass cloth to the inside. the only place i did do this was the helmet and the chest peice, and lucky i did to because on the way to a party i dropped the helmet! instead i used good old paper mache, not the flour/water mix but the stronger glue mix. this gave it enough strength to be worn for a good long while, while keeping keeping my already thin wallet happy.
For the visor i just used a yellow tinted file folder, hot glued to the inside of the helmet. after i had finished with the outside of the armor and the Elmers wood stuff had dried i sprat painted a base coat of green, the i used black spray paint to add the highlight/shadows effect. then for the bicep pieces i used the last of my silver and a different green to add a camo/worn look. it's too bad that i couldn't do this for the entire suit though.
overall i probably spent a total of around $100, but i had to by a respirator for using the resin, therefore it was probably closer to $70, not bad for a full suit of armor!