If you like Valhallans, you can make them pretty cheaply from Warlord games Winter Soviet Boxes
https://us-store.warlordgames.com/collections/soviet-army/products/soviet-winter-infantry-plastic-box-set
All you need to do is order some sort of sci fi weapons from another company to get them looking properly Imperial Guard like. I'd recommend Victoria Lamb stuff, her weapons are smaller and scale well with these guys. These are the rifles I used for example.
http://victoriaminiatures.highwire.com/product/5-laser-rifles They slot right into the WWII Soviet's hands like they were made for them after you shave a couple
MM's off the stock.
Best part is it's actually cheaper to build using these guys for the most part. The only expensive part is finding heavy weapons. If you're just building riflemen and the odd special weapon, these guys are cheaper than
GW.