at current difficulty
The expected generation output, at 3500000.0 Mhps, given difficulty of 148819199.805, is 11.8275922046 BTC per day and 0.492816341858 BTC per hour.
you are increasing to 3.5Th/s of mining hardware for $7500 ?
great deal - but in 2 weeks difficulty will have gone up another 30-40%, so you will need more than 3.5Th/s to make the estimated returns you claim.

currently 4module avalon earns ~ 0.34BTC/day (before power costs) so to earn 2.5BTC/day you would have 6 of them?

Power in AU is expensive compared to many parts of the world - one of the reason so many AU GPU miners quit BTC mining in 2011 when price dropped from $33 to $3

I have been running a Pool in AU since June 2011,
If you would like to talk privately PM me, I may be interested if you can prove some of these claims
Cheers
Graet