Wholesaling newbie- Should I keep cold calling?

[Taylor Mosby]

I just got started with real estate wholesaling and I am trying to get my first deal by the typical method of cold calling off-market property owners and asking if they'd consider a cash offer. Specifically, I've been targeting absentee owners of vacant properties with tax liens, pre-foreclosures, and tired landlords. 
I've been doing this for about 2 weeks now for 2-4 hours a day, but I have yet to make any measurable progress (no leads at all!). Most of the homeowners that pick up say that they've been bombarded with calls already and they're just not interested.

I'm not afraid of rejection, but I am concerned that maybe this is not the most effective use of my time. I've made hundreds of calls and most are disconnected, rejected, or extremely rude. Also, I've spent about $100 to use PropStream and Skip Tracing services. This may not be much to some, but I am a college student so it is a considerable amount. I am not allowing myself to give up on wholesaling, but I must admit that at times it is discouraging. 

For those with experience or knowledge in wholesaling, should I continue to cold-call? Is there a more effective method to generate leads these days?

I am open to any advice at all!