Certainly the least expensive option would be an internet site to site VPN over whatever Internet access is available. However, that Internet traffic may just be riding the same network backbone as your MPLS connection and, in the event calamities, it may also go down.
Certainly the more expensive but most reliable option for DR would be VSAT. In other words, with VSAT you are going over a complely seperate network.
As long as you are okay with the satellite latency and the price is acceptable, i would go with the VSAT solution because it is a diverse path.
Hope that helps!