Attic Insulation methods in Florida?

[Tim Kaminski]

Hello BP!

Have a 1923 duplex in Tampa, Fl with no attic insulation but 2,000 sq ft of attic space.  No big deal, but after learning that it will take around 80-90 bags of cellulose to achieve the minimum R-30 rating for Florida, ($1,000), I decided to look at other methods!

Have looked into other possible methods, Radiant Barriers and Spray Foam.  Both intrigue me but would love some input from ppl who have done these themselves or have other suggestions.  

Radiant Barriers would seem like a top frontrunner with Florida's heavy sun but wondering if it would be enough insulation and how much it would deteriorate the shingles on the roof.

Spray Foam is far too expensive to have others install but is still pricey for DIY.  Seals up airs gaps and blocks moisture but doesn't let house breathe and if applied wrong can have negative effects.

Obviously would want something I can do myself and achieve a price lower than the $1,000 for blow but want to make sure it is effective.  Have installed central AC and want it to not be overworked.  Any help is much appreciated!