You can spend the $15 a bag for premixed Roots, Happy Frog, or Fox Farm or any others offered. I've used the Happy Frog with good success on some indoor soil, but I think the soil had very little to do with my actual success. It's just nice because it's already got peat & perlite in it which helps with air exchange & drainage, has beneficial bacteria & humic acid, and has been mixed/stored indoors which will greatly reduce the ammount of insects that will come with your soil.
Personally, I like to save money and create my own mixes, and I think as far as bugs it's more about maintainence. Even those pricey soils will sometimes bring in mites, blackflies, & whatnot.
Last mix I did contained the following:
EarthGro potting soil
Perlite
Peat Moss
Vermiculite
Steer Manure
Earthworm Castings
Blood Meal
Bone Meal
Garden Lime