Need advice on upping food size.

So my ball is currently on f/t adult mice. This however is becoming to small so its time to up the size. The only problem is my local pet store (petco) goes from adult mice straight to small rats. I'm concerned that if i try to feed her a meal to big she could damage her throat. So i have a few questions:

If a meal is too big, will a ball eat it anyways? In other words, will she reject it if she can't eat it?

I know that the feeder should be about the same girth as the snake, but is there a little play on this measurement? Like can the rat have .5" (totally made that number up) bigger girth and be fine to feed to my snake?

I looked online for feeders and unless I'm missing something it seems very expensive to order them. I can't store a hundred rats and the shipping is almost as much as the feeders themselves. I'm hoping I don't have to order them online but I will if i have too.

Logically I'm assuming the only way to be sure is too compare my ball's girth with the small rats girth, but i would like a second opinion.

Sure there is alittle play in the girth rule. A tad larger is fine but a snake can try to eat something that is to large.

Another good method of selecting feeders is feeding prey that weighs in the range of 10-15% of the snakes weight in grams.

Ordering online can actually be cheaper especially compared to what you are spending at Petco. The key is to order enough that the shipping evens out the price. I used to make two big orders a year and have a small chest freezer just for my rats.

You may cruise your local craigslist or post an ad looking for a local rodent breeder you can buy just what you need from.

Before I found a local breeder I used Rodent Pro and was very happy with them. They also have Hot Buys where you can score some really cheap feeders.