I made a structure for T25 the other day. If you do T10K stacks, this structure will be just fine for up to three tables (for one table, it should end by 3K/6K level with or without rebuys). For a 3/4.5/6 hour tournament, use 10/15/20 minute levels and breaks (it should end a bit sooner, but it allows enough time to definitely have a winner).
For chips:
8/8/4/7 stacks will get you T10K, which is probably best of you're looking to spend the minimum (which I would assume you are since you're splitting costs). You could get by on a 300 chip set with the amounts below:
If buying in barrels of 20 (preferred).
80/80/40/80/20
10 starting stacks
Color up T25s and T100s with T1Ks
Color up T500s with T5Ks
If buying in sleeves of 25:
75/75/50/75/25
9 starting stacks
Color up T25s and T100s with T1Ks
Color up T500s with T5Ks
(For a tenth stack, use 0/0/14/3 or 0/0/4/3/1).
25/50
25/75
50/100
75/150
100/200
150/300
Break - Color Up T25s
200/400
300/600
400/800
600/1200
800/1600
1000/2000 or 1100/2200
Break - Color Up T100s and T500s
1500/3000
2000/4000
3000/6000
4000/8000
6000/12000
8000/16000