just an idea (i am full of them :):
the Reflectix is more expensive of course, but the sheets have a lip for stapling, so you can attach them in a row with closing stapler to each other and then fold in accordion fashion for storage. and on top punch holes with puncher and hang them even on T-pins or long thumbtacks (they make very small holes): the plastic is strong enough not to rip i think, but you can always reinforce the top with duct tape. no need to recycle, just hang and then fold when not needed. you can do 2 rows (half the wall) so it is easier to hang.
