If you like rolling your owns the two Rollei CN200 (negative) and CR200 (reversal) are also sold as bulk film, final cost is below €2,00 per roll. I'm going to try some rolls of both products and if I like them I'll begin the rolling.

There are some very cheap film around here in Italy, Kodak Color Plus 135/36 is at €1,70 or Ferrania Solaris 135/36 at €1.80 at one of my favourite online shops www.westernphoto.it which also sells through eBay. They ship by courier I have no idea what the cost and taxes would be for shipping to Turkey, but I find them quite professional. In case you would like a product they don't have, try asking them about it, they might have it within a few days. Those cheap negative films are typically also sold, I suppose, as "private brand" products.