Called up Ridpest. Rentokill, NLC and Okin on the phone to inquire about getting Termite control

Ridpest - the sales man says that with my current renovation stage, should go for the drilling system. Not recommended to spray the roof truss, very poisonous for resident. (using local chemicals)
Rentokill - the salesman recommend the drilling system and when I inquired about the Termguard Reticulation system, he says it is not suitable as it is costly (+/- 20k) and only can put in before the house is built. (using Bayer)
NLC- The salesman recommend a package, Drilling and Sentricon system together.
Okin - the salesman says that they only have Sentricon System.
All need to look at the house before giving actual quotation.
From the initial discussion, the impression I get is.
- Drilling- Guarantee up to 5 year better to use Bayer.
- Spraying truss - not recommended, termite comes from the ground thus if you kill the queen then the roof termite will die off too.
-Termguard Reticulation system - pricey like hell and the piping need to be set in before house is built.
-Drilling is the cheapest 2k-3k
-Sentricon- 3-5k and yearly maintainence arounf 700 - 1k .
My house has a slight termite infection, not major but need to clear of before I move in....
Any suggestion on which way to go?!?