Pasadena - large group
Daisy Mint probably can't hold a group of 30 anyway...
I second Saladang Song.
Also consider driving a little bit to Arcadia area and go to one of the Asian/Chinese places there. Lunch is super cheap ;) Of course, the ambiance will not be nearly as nice as Saladang Song and such ... but consider Newport Seafood, Phoenix, etc.
I've held several large parties at Saladang Song. You may want to pre-arrange a prix-fixe menu with 3 or 4 items to be served family-style. That way, you can come in close to your budget and still offer a variety of dishes. But if I recall correctly, they do offer lunch specials that are reasonably-priced.
Also, Radhika's (next door to Green Street) offers a lunch buffet for around $10. It's a great site for kids, bc of the nearby shopping arcade and fun British telephone booths.