The new Nurglings cost too much ($12 CAN per base of 5 Nurglings), I'm getting the Archive ones for $10 per base. The archive ones are better anyway, and you don't have to drill the bases to glue them in. I could get them for $8 per base if I only wanted 4 Nurglings per base, it's much easier this way.
That, or you could get a ton off of eBay for really cheap (Silverthorn got a whole ton, something like 20 bases, for just a little bit of cash).