Hi Tansu,
an empty BW 7.4 is about 25 GB and even with room for cache, HANA services, and temporary memory it fits nicely into 100 GB of RAM.
Not sure how much data you want to load and how long you will need such environment. You could check the trial offer (you could install the missing pieces yourself easily):
SAP BW Powered by SAP HANA – Trial Offer | Sales | Line of Business | SAP HANA Marketplace
Regards,
Marc
SAP Strategic Customer Engagements (SCE)