4000 or 7500, you still have to sweep every aisle.
And I can't imagine that the security cost increase would be an issue. You'll notice that the security protects the court, players, and entrances. 4000 or 7500, you've still got the same number of players and entrances, and same court-space.
I have no problem with $25 tickets below the concourse on the sides. But I think that they should be a bit realistic and make it more affordable for uni students, young couples, or people half-interested in the sport. Offer cheaper tickets above the concourse and behind the baskets and fill the stadium for every game. The potential alternative is that the average crowd drops and the Dome loses its reputation for providing a strong home-court advantage and great atmosphere.
I hope the rumour that they're 1000 down on sales isn't true, and I hope they pull crowds, but last season's win-loss record was the worst in 14 years (11-15 in 1990). They've regained some show-time and a crowd favourite in Farley, but lost one of the best and most passionate players in Cattalini. I think the squad will be competitive in the league, but there is yet to be any real hype being built.
This season I'd try things like:
Three for two: 3 games for the price of 2 (above concourse, limited offer, once per person per season) to up-sell people wanting to just see Kings vs Sixers for example (why not pay for another game too, and you get a third free).
Referral bonuses (hats, lanyards, stress balls -- all that kind of stuff is a lot cheaper than you'd expect).
Newbie Packs that you could buy for a friend (comes with a couple of tickets, advice on getting to the Dome (where to park, how early to get there), and then a little guide for those new to basketball, explaining the travel calls, various referee signals, fouls, bonuses, who's who, etc).
Game and food: $20 concourse ticket gets you in and a $4 voucher for food/drink at one of the stalls (not the walking sellers). Many people would add some money to that rather than just get a drink and a chocolate bar or something.
Business tickets: 10 tickets for $175 or something. Require an ABN/ACN or order on official letterhead. Get a group from work together and drag along those who might never go to a basketball game in their lives. Anyone who can bring in a Business booking gets their own ticket for free (someone could subsidise their own attendance year long by promoting this kind of thing a bit).
People who haven't been to a game will have preconceptions or have not thought about attending -- make them curious, spread the word, etc. If someone says "come along to the footy, Sturt vs Norwood" and it's $5-6, why wouldn't you go along? $12 for the soccer?
If it was $20-25, you'd have to think about it and I daresay that many would turn it down.