Made some updates to my original post. I can't weigh the DME, so 1/2 cup, cup, etc. would be appreciated.
After learning what crash/dump is, I won't be doing that. The wife wouldn't love a gallon carboy and blow off in the refrigerator.
I keep the ratio of about a 1/2 cup to 2 cups of water ratio. I don't know if this is adequate, but it was what I was told when I first starting making starters.
Eh... She'll get over it. There won't be a need for a blow-off at that point. Just wrap some sanitized aluminum foil over the carboy opening. Actually, I do that from the beginning. Typically if I brew on Saturday, I try and get my starter going on Monday evening or Tuesday at the latest. I'll start cold crashing in the fridge when I get home from work on Friday (3:00ish) The yeast drops out nicely and I pour off the spent beer. You really don't want to add that to your actual brew that you've worked so hard on.
I suggest going ahead and investing in a decent digital scale. The 11 pound scales are adequate. I got mine on Amazon for like 20 or 25 bucks. You'll eventually use it for measuring DME, priming sugar, hops, grains, and any other additives to your beer.