We feed our bottle babies 4x a day for the first 2-3 weeks depending on the kid and then 3 times a day for a week then 2x day for a week and after that depending on how good they are doing just once a day for a while to give them the extra nutrients. I live by the rule of less per feeding and...
I am in the Eastern U.P. of Michigan and I pay no more then $2 a square bale and for round bales it depends on the size. Usually I buy from a farmer down the road who has 6x6 bales that average 1400#, stored inside and are a mix of grass hay and alfalfa for $30 a bale.
If the grass has been eaten down and you are supplementing with hay already then I think they would be fine if left out with access to the run-in. My mini mare gets to go out on my small pasture once I have let the "bigs" mow it down. There is not much grass here to begin with and I keep my mini...