You live in AZ I bought my kit in New England. Try AutohauAZ in the Phoenix area, they carry MB, BMW, VW, German car parts. I am sure they have these parts. My guess the reason your belt split is because one of your idler pulleys has a bad bearing and as a result it is no longer in alignment with the other pulleys. When you install the new pulleys and belt you will also notice a quieter running engine.
Good success.