If you're doing ranged in my opinion I think the minotaurs on the first floor of the Stronghold of security are good. They're about 22k p/h and you get arrow drops from them

In the case of magic, I'd go with alching. Go on the GE database and find something that has a similar price to it's alch value. You won't loose alot but you're definatly not going to gain. Another method you could try could be Superheating steel. You profit from that so look into that provided you have a high enough Smithing level

~ Jeki ~