I run my 20g with 4" of southdown, a rubble pile and chaeto. I got small bags of live sand from several LFS to seed it (you could tap local reefers for this) and I keep a cucumber in there. I hear micro stars are good too, but I've never seen them for sale locally. It would probably wouldn't be a bad idea to include cerith and nassarius snails.
If you can go the top of the line route, put the same lighting over your refugium (pc, t5 or mh) that you have on your display. On the cheap side, do a search for Melev's lamp or you can buy 6500k pc bulbs (either with or without integrated reflectors) at most of the big hardware stores.