I agree about the irony and I enjoyed your post above about it.

I take the irony to mean -he didn't mean to be unkind, however it ended up not being kind- 1000 pounds was a sad return for their affection.

Or did you mean the irony is that in fact he did mean to be unkind?
Perhaps it doesn't matter since the result is the same.

How much of Austen's irony is directed at society that undervalues women? Could the Old Gentleman have thought that the girls would remain at Norland until their marriages and thought that was enough?

You make a good point that easily John Dashwood could have spared another 1000 a-piece, but would that even have been enough? I'm still interested in the money aspect- how much would it take to keep make them comfortable, or for a suitable dowry? I don't believe it says the value of the estate?

So on to John Dashwood...(from ch.1)
"Yes, he would give them three thousand pounds: it would be liberal and handsome! It would be enough to make them completely easy. Three thousand pounds! he could spare so considerable a sum with little inconvenience." He thought of it all day long, and for many days successively, and he did not repent.

We know about John Dashwood's selfishness from his introduction just the paragraph before, so I wonder can we believe that 3000 pounds IS really liberal and handsome, enough to make them easy?