As of when this post is being made, the thicc items case sells for 23 million roubles on flea market. That's a lot of money for most people and definitely for somebody trying to learn the game.
Assuming you have level 2 stash upgrade: (costs 3.5 million roubles and some junk items) EOD users have 10×68 stash size, 680 slots of usable space. Standard edition users have 10×28 stash size, 280 slots of usable space. Upgrading your stash to level 3 will get you 480 slots of space. Costing 8.5 million roubles and leaving you with about 14.5 million roubles left.
With 14.5 million roubles you can easily buy NORMAL items cases for about 1.9 mill a pop. 3 items cases is about the same size of the thicc items case. (thicc items case = 196 slots, items case = 64 slots multiplied by 3 is 192 slots.) That means you can pretty much buy a splitted thicc case for about the 4th of the price.
With around 300 extra slots of stash size, you'll also have about 9 million roubles left over to do whatever you please with.
DO KEEP IN MIND: I am making this ASUMING that a standard edition user has already upgraded their stash to 10×38 slots. This is also intended for people who are low on stash space and are trying to learn tarkov (which is why the extra 9 million is so useful)