We've talked about this on here before. The going rate everywhere seems to be between 7-9K Baht per year, which includes a yearly filling of the in-foundation gas pipes under the house to prevent termites.
However the service is for insects, not large centipedes and the like I think the OP is describing. Not for rats, snakes, snails etc., either. That's a whole different deal and chemical substance, and an entirely different price structure as well IMO.
I think the concentrated sprayer liquid the OP will find in shops is for insects only.
The service we use puts 2 capfuls into about a 10 liter sprayer so it is potent stuff and gets rid of ants, cockroaches, spiders etc., but we still have frogs, toads, snails crawling around after it is applied. Pete
