People buy in on average 140 BB
Ok, so here goes. Without knowing your budget and how many chips you ultimately want or can afford here is what I would want.
0.25/.25 and initial avg buy in of $40 with 8 players
I want to start everyone with 20 - .25's, 20 - 1's, 3 - $5's which is
160 - 0.25's
160 - $1's
24 - $5's
For the 4-6 rebuys I'd give the first two rebuys the same starting stacks and then any rebuy after that I'd give out 20 - $1's and 4 - $5's
So I'd want this breakdown which is an $850 bank which is 21 buy ins.
200 - 0.25's
300 - $1's
100 - $5's
0.25/.50 and initial avg buy in of $75 with 8 players
I want to start everyone with 20 - .25's, 20 - 1's, 10 - $5's which is
160 - 0.25's
160 - $1's
80- $5's
For the 4-6 rebuys I'd give the first two rebuys the same starting stacks and then any rebuy after that I'd give out $20 - $1's and 11 - $5's
So I'd want this breakdown which is an $1850 bank which is 24 buy ins.
200 - 0.25's
300 - $1's
200 - $5's
20 - $25's
0.50/$1 and initial avg buy in of $140 with 8 players
I want to start everyone with 20 - .25's, 20 - 1's, 23 - $5's which is
160 - 0.25's
160 - $1's
184- $5's
For the 4-6 rebuys I'd give out $20 - $1's and 14 - $5's until they are gone and then go to $25's
So I'd want this breakdown which is an $3100 bank which is 22 buy ins. Even without $100's and $500's you have more than enough to cover your game.
200 - 0.25's
300 - $1's
300- $5's
50- $25's
All three of your games you will want 200 - 0.25's so you're not making change every single hand for the blinds.
2 of your 3 games you will want the $1 to be the workhorse chip which means minimum of 300 of them.
The 0.50/1 you want the $5 to be the workhouse chips so you need 300 of them. 850 chips to cover 3 different stakes is pretty damn good. Of course if you want to future proof the set you can go with 80 - $25's and 20 - $100's to make it 900 chips in total.
Hope this helps!
Good Luck!