The easiest and cheapest way is to run a native agarose gel.
Check the small protocol at the bottom of >this page<
, entitled "Native Agarose Gel Electrophoresis of RNA".
-All gel plasticware (casting tray etc.) must be thoroughly washed with soap and rinsed in ddH2O (best if mQ-grade water)
-TBE can be autoclaved. In my lab we use 1xTAE prepared from a 50x stock, it gives good results too, but TAE shouldn't be autoclaved. Prepare from mQ-grade water and be clean - remember that autoclaving can reduce the RNAse burden, but can't make contaminated water RNAse-free (and you shouldn't add concentrated DEPC to a solution with amines like Tris).