I use mealworms and have only ever had to buy the single tub of them as they are stupidly easy to keep and breed although I wouldn't use only mealworms for the diet.
Considering the fact you are planning on only getting a rosie you will probably be as well just buying a couple of crickets / locusts each week to feed it, I've never used crickets myself as I'm always reading too much **** about them either the noise or stink or they have mites or even worse are probably contaminated with something and kill the spiders that eat them
or heck they even eat the spiders sometimes
, locusts however I have used and they are easy to manage, quiet and don't smell, though you may want to take some scissors to their jumping legs before offering them 
this is all assuming it hasn't gone on hunger strike which they seem to do frequently i should add and that you haven't got one with a psycho attitude
personally I'd forget getting a rosie and get something with a more reliable temperament and appetite like a Pterinochilus murinus
Considering the fact you are planning on only getting a rosie you will probably be as well just buying a couple of crickets / locusts each week to feed it, I've never used crickets myself as I'm always reading too much **** about them either the noise or stink or they have mites or even worse are probably contaminated with something and kill the spiders that eat them



this is all assuming it hasn't gone on hunger strike which they seem to do frequently i should add and that you haven't got one with a psycho attitude

personally I'd forget getting a rosie and get something with a more reliable temperament and appetite like a Pterinochilus murinus
