Here are some very affordable hotels, ALL on Munras Avenue in Monterey:
Monterey Pines Inn
Aura Inn
Days Inn by Wyndham
Padre Oaks Inn
The Inn at 1252 Monterey
Rodeway Inn Near Downtown Monterey
You can find these, as well as about a dozen more on Munras Ave. by searching "hotels" in Monterey in Google Maps.