I know there is a guy on this site that sells complete starter colonies for a reasonable price
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or if you wanna go at it by yourself there are a few good roach sellers online.
buydubia.com
dubiadeli.com
kimbrellscoldblood.com
this is to just name a few. I suggest doing research, find the best price with the best reviews and go from there.
I started my own and every now and then have to resupply and I personally go thru Kimbrell.
I will tell you this dubias are sooooo much nicer than crickets, crickets just really creep me out still good feeders tho, I hate any flying or jumpy bugs.
Hope this helps