I've not been able to find any decent deals online for places to stay in eastern europe.that is exactly the problem !
if you want to be happy in Rome , do as the romans ...
may be (only a suggestion

) in eastern-europe you cannot get any cheap deal ONLINE ?
why is that so ? :
because peoples selling trips&stays know just too perfectly well that the one looking for "Online things" are the ones to be ripped-off ... (i may come as a surprise , but you know they do it for money !!!)
you would be amazed what kind of deals you can get once "In place" !!
like if you want to find good , decent and quite cheap rental flats in Kiev , go to the train station , in a street close to it (sorry i don't remember the name) there is a few "babushkii" renting flats ... for about 1/3 to 1/2 price of anything you would find home ....and online !
if you can have a local "talking " the price , do not expect to get cheaper but a nicer flat ...!
so my advice : book your trip and your stay for the first one or two days , once on spot , you will decide what is best !!