At Warsaw-Babice, Stork Aviation used to rent a nice Robin HR200-120 (F-BUQG) with
Lycoming O235, for 400PLN including fuel (although the hourly rate probably went up). They have a FB page; it may be worth checking them out.
At Brzeska Wola, 70 km south of Warsaw, FlyPoland have hour building packages on C-152s or 172s which can include accommodation.
In Hungary, CAVOK.hu have decent HB rates on Viper SD4, Tecnam P2002-JF and Aero AT3 R100.
Cheers 