I don't know if Dallas still has the same ticket policy, but I lived there from around '04 to '07 and they always had sweet ticket deals.
Every game, 2 hours before tip off, if you went to the box office, all unsold lower level single seats were $30 bucks, all upper bowl single seats were $5. Problem is they won't sell you 2 together (single tickets only), but they would try to put you close together if you asked. So me and my buddy would go down to games, and when we wanted to sit in the lower bowl they would put us as close as possible, maybe 1 row behind each other (like I'd be L11, and he'd be M12 or something like that, so it was still pretty easy to talk to each other), usually we'd be able to still sit together anyway because the seats next to us would be open. The rest of the time we'd just buy $5 upper bowl tickets, and very easily find 2 seats together
As popular the Mavs were at this time, they never really sold out. Never a problem finding 3-4 upper bowl seats together. And the only time I remember no tickets being available for this deal in the regular season was when the Lakers came to town.
If you haven't bought tickets yet, I'd definitely check this out. Even if you have, I would go to the box office anyway and see if they still have this deal so you know for next time.
Remember when the Mavs gave free plane tickets to everybody in attendance? Me and my buddy were in the building with $5 tickets.