I agree with all of the above so far. I am currently "breeding" angels in a very low tech, low cost set up with tanks I have around. I had two pairs in a 30g with a divider and a large sword on either side. I have seen "breeder setups" that have pairs in rows of tanks that looked like 10g's. So, I don't think a large tank is necessary for just spawning the parents. Both pairs would parent raise for a while and it was great. On the original spawn I left the fry in the tank until they were dime size and it was too much for the parents, you know how teenagers can be. Now, I would let the parents "raise" the fry until they were too large to to be picked up by the parents mouths(which is a really cool thing to see). Then transfer to another tank fpr grow out. The marble pair would spawn almost like clockwork two weeks after I took the fry out. The "blusher" pair I had weren't as regular. But, unfortunately one of those two died suddenly a little while ago. I think due to a parasite from some blackworms I was feeding a while back. I lost some pelvicachromis to it also. Now, the marble pair is in their own 45g planted corner tank, and they have been in there about a month and they do a lot of leaf cleaning, but no eggs yet.
As far as raising the fry to saleable size, the bigger the tank the better. I originally tried raising the fry in two 10g's but they grew a little quickly and then growth slowed. Now, I use a 55 I freed up to raise the fry and they grow fast!! If I had a choice to set up a small spawning set up I would use a divided 55g with two pairs spawning on swords, it looks really cool and I think the hormones or whatever released by the other fish in the tank seems to spur spawning. Then I would have a 20-30 g for initial grow out and a 55g at least to grow them out to a small saleable size. IME- it does not benefit you to grow them out past dime size. For grow out food, the best IMO is always live baby brine shrimp. I tried afew other things but not with the same success. Hatching them is a little work, but definitely worth it.
Yesterday I came to home to find that two of my four still pretty juvenile angels had spawned in my 75 g community plant tank, just like their parents did two years ago. So, know I have two pairs again and hopefully they are as good parents as they're parents have been. Spawning angels is a rewarding experience, and it seems like some of the varieties are pretty easy to spawn.