OK, so! Here's what I've got lined up for the neo-Sovs so far. I envision the army as divided into three groups: regulars, militia and Guards. Regulars are going to be mainly Copplestone neo-Sovs. By my count I have enough to do a rifle squad plus LMG, an AT section (although I could do with another loader) and a command squad (with some em4 police thrown in as sort of NKVD types; their hats aren't quite Russian-looking enough, but they'll do). I've also got the aforementioned sniper.
The Guards are going to be the Fantasians. I have enough of them to do a squad, a sniper and an HMG team.
The bulk of the thing is going to be the militia: a wide variety of miscellaneous futuristic guys from many manufacturers, with a leavening of Copplestone neo-Sov partisans picked up off ebay on the cheap to bulk them up. I am also going to add some Back of Beyond commissars I found in the bargain bin at Orc's Nest to give them a little motivation.
Vehicle-wise, I'm definitely using a Robogear "Varan" I got on eBay (for less than £1 when you average it out) and maybe a couple of their smaller walkers. The Varan is quite Katyusha-like, which is something I was hoping for.
So, basically, four infantry sections, a command squad, a couple of snipers, and at least one vehicle. The only things really missing are a couple of mortars and a tank. My current thoughts are 1st Corps WWII Soviet 82mm mortars, which come in a pack of two for £8.50. Tank-wise, I'm strongly tempted to follow Ironworker's example and scour charity shops for a cheap plastic tank I can stick bits on.
Unless anyone has any alternative recommendations?