I think the goblins are a fantastic buy for the cannibals as they have roughly just about as many as you'd need and end up costing less than £1 per model although in my case I settled for some cheap zombies from Ali express. I'd imagine i'll be waiting a while for them to arrive although i'll be sure to post some pictures here if I get them to a satisfactory state( I need to figure out how to paint skin on models as my recent attempts have been lackluster)I would add; for cannibals I've seen people make great use of the LOTR goblins: https://www.games-workshop.com/en-GB/Goblin-Warriors-2018
I'd also second the Maelstroms edge broken infantry. If you've got some bits laying about (particularly torsos) you can use the spare legs and arms you get with that to make more than 6 guys out of it. Would recommend having some spare heads ready too though - many of the heads on there are very alien.
I've bought the Maelstrom edge broken infantry box to check them out. I'm strongly considering making video guides for hanger-ons, hive scum and other necromunda models with kit suggestions and tips for kit-bashing if I get some decent conversions done.