Never been to coron but I've been to Puerto Prinsesa and El Nido, you'll find cheaper accommodations at the airport itself or maybe ask around the locals, maybe. That's based on what I experienced in PPS Airport.
madaming cheap accomodation don near the market.. pero gagastos din talaga kayo kasi wala naman kayo magagawa kung don lang kayo sa coron town mag stay.. you need to hire a boat for island hopping and snorkelling and to see the sunken ships.. kung 4 lang kayo.. you better find some other group na pwedeng samahan para maka mura kayo.. kung food naman.. madaming kainan don.. for 100 pesos per meal.. solve ka na.. some even less.. parang mga carenderia lang..