Walmart sells the cups like Tupperware has, you get 3 or 4 in the pack. They are great, they are not "sippy" cups, and they don't suck to get the liquid out either.
My daughter, who is 7 now, has had speech delays since she was little, and we threw out all of the "sucking" cups when she was little, it did help. The tongue has muscles in it and they are used in different ways to make different sounds. So children have to get used to using those muscles in different ways....other than just the sucking muscles.
Try the cups from tupperware or from Wally World. They are just plastic cups with snap on lids on them....with a small slot for drinking. They will spill, but only drops will come out if you catch it in time.
I quickly got out of the habit of letting my kids just walk all over the house with any type of cup, they could only have drinks in the kitchen, and not all the time. It sure helped with the potty training too, when they weren't drinking all day long.