When I was in yeshiva in EY a number of the guys started wearing ponchos in the cold. It was the style, a bit hippyish. We asked a big rav about the ponchos. He recommended that we put on tsitsis. There was a shayla regarding both the length of the long ponchos, as the strings would drag on the ground as well as the materials of the poncho (largely synthetics) vis a vis bracha (I believe we made one).
When in doubt ask a shayla to your rav. If the costs are too high, ask your rav about the possibility of rounding off a corner of the begged.