i got a couple of sunsun double t5 lighting units off trademe for about $110 a piece. I've had sunsun filters before and they seem fine (though not very efficient and ignore the advertised output as it drops off pretty quickly). that said, personally i would go for the aquaone filters.
if you didn't want to sell the fish, best bet would be to set up the new tank for them and go with a community tank. clown loaches get pretty big (or at least they should do if they're in the right conditions), as do angels, and need much more space than a 620t. that said i don't think you'd have too much trouble selling them (and they won't even be close to full grown fish). if you wanted to look at the possibilities for an african tank you're more than welcome to come check mine out, just pm me. my tank is about the size you're looking at and i reckon it's turned out pretty good.