My suggestions for spacious,comfortable accommodations for a moderate amount of money would include, besides Coral Bay and Belizean Reef that you mentioned:
Blue Tang Inn
Most (not quite all) of these you could get for under US$100 in September. Keep in mind that September is the slowest month for tourism of the year in the Caribbean due to the threat of hurricanes and the fact that families have children that are back in school that month.
Ramon's has some nice units, but they tend to be expensive. The cheaper units in my opinion aren't in the same class as the accommodations at the high-value condotels such as Banana Beach, Belizean Shores and Mayan Princess.
Belize books and publications by Lan Sluder:
Belize First Magazine (http://www.belizefirst.com
Fodor's Belize & Guatemala Guide (new 4th edition coming this summer)
Adapter Kit: Belize (the first and only comprehensive guide to living, retiring, working and investing in Belize -- a best-seller on Amazon.com)
San Pedro Cool (the first and only visitor guide to Ambergris Caye)
Belize First Guide to Mainland Belize
UpClose Central America
Belize Book of Lists