nutrients-first time grow

hey everyone
so i ve had3 girlies going now for 3 weeks, and theyre comin along good . its my first grow so budget and supplies are pretty low. i have them under 2 small 33 w shop lights, and a yellow light to keep some heat up. i have them in miracle grow soil(didnt now what else to get ) and have been feeding them the best nutrient i could find at wally mart and it says its 24-8-16. im not sure what i need to be feeding these seedlings.

so anybody know any really cheap and/or easy to find nutrients, foods, what ever will help em out?

any other tricks and suggestions would be much appreciated

Ive gone to Lowes/Home Depot/Wal-Mart to look for nutes bc we have no garden shops around town. Basically thats about the best your prob gunna find if you dont have any garden shops.

Im also doing my first grow so Im not an expert, not even a beginner lol. but I have found from reading threads that Foxfarm nutes are amazing. Not sure if you are able to order from online, but if so, I found this combo deal and it seems to be a pretty good price (not rly cheap tho)

Foxfarm Nutrient Trio for soil AmericanGardenSupply.com