Are my sentences ok?

1. I am 10 dollars short to be 100 dollars. NO

2. I am short 10 dollars of 100 dollars. YES

3. There are still 10 dollars short of 100 dollars. NO

We/They are still ... .

4. There still are 10 dollars short to make 100 dollars. NO

We/They are still ...

Fluent native speakers (adults and older children) would omit the ugly repetition of 'dollars', and fluent native writers show numbers as words - e.g.:

I am ten dollars short of a (or one) hundred.
I am ten short of a (or one) hundred dollars.

You B.Lit's are way too anal.

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Write out numbers that require no more than two words, remembering that a hyphenated number between twenty-one and ninety-nine counts as one word. Some writing manuals will suggest that whole numbers from zero through nine should be written as words, and numbers from ten on up should be written as numerals, especially when the word modifies a noun as in five students or two professors.

http://grammar.ccc.commnet.edu/grammar/numbers.htm

Even in what I believe North Americans call 'grade school', English teachers would score through the figures in e.g. he is 2 chisels short of a toolkit; she is 2 sandwiches short of a picnic; he knew how many beans make 5; he's got the key of the door, never been 21 before; and certainly in reported speech there are three hundred and sixty-five (not '365') days in a non-leap year.

You B.Lit's are way too anal.

Just think what you might have been able to offer your students if you weren't so anal, C.

1. I am 10 dollars short of 100 dollars …or
1. I am 10 dollars short of 100 …or
1. I'm one sawbuck short of a bill

https://www.google.com/?gws_rd=ssl#q=slang+for+100+dollars

2. I am short 10 dollars of 100 dollars. Okay but collo omits last "dollars"

3. There are still 10 dollars short of 100 dollars. Awkward. It's still a Blue Swimmer short …. We're still a tenner short...

4. There still are 10 dollars short to make 100 dollars. Awkward. 4. We're still 10 dollars short of 100

Thanks to everyone.