Siberian coins are rather rare (denga, 1 kopek, 2 kopeks, 5 & 10 kopeks): these coins minted during the Catherine's the Great reign.
Russian Tsar gold and platinum coins Here's one 1 kopek coin in a better condition: Back then Russian coins weren't insane expensive - this was like less than 2 dollars at most.
There are alot of interesting, and rare Russian coins out there... like gxseries said the gold and platinum ones especially. But as far as something more reasonably priced, but still quite collectible, I always liked the Russian Imperial silver Rouble coins. The second coin you posted looks quite nice. Here is one of my favorite Russian Empire coins.
The 1915 3 Kopek coin you showed is very nice. Here is some more info on it. According to my World Coins book, the 1915 3 kopek was struck in Petrograd without mintmark. My book lists the mintage for this issue as 19,833,000, and the values as follows: Fine - .75cents. VeryFine - $1.50. Extra Fine - $3.00. and $16. in Unc. However the Krause I am getting this info from is the 2004 edition, and those prices for EF and Unc. seem a bit low to me.