So many that I've had to turn on my 'silence unknown callers'.   

@Andrew SmithVery likely that’s wholesalers.Get some sort of interest from you that you might sell and send it out to a list of buyers.There’s subscriptions you can buy that uploads a ton a phone numbers and addresses that cold callers use to cold call.

Especially from the standpoint that the caller was looking at getting into their first property. 

You need a follow-up plan, CRM, phone, callers, etc. to be effective.

Make them happy to talk with you, instead of looking at the caller ID and... groaning.Re vetting -Highly Recommended Suggestion #1 - see if they answer their phone on the first call, or return your call immediately.

It's the same concept here: we want our callers to filter out the bad stuff. 

.) - Hire a cold caller on Upwork ($5-$10/hr + commissions for deals closed)- Set them up on a Dialer like Mojo Dialer ($100/mo)- Subscribe to a proper CRM to manage leads like Podio (~$50/mo) - Depending on how much time that you have yourself, then I would go door knock a certain list that you pull (or certain zip code you want to target) since door knocking is free. 

But, some callers are insistent that I need to sell to them (even thought I tell them it is unlikely they can meet my price) or keep calling even after I tell them to go away.  

However every caller and lead gets a card, and it makes following up very easy since I can see everything in a single top-level view.

However, even if folks pick these up, they still call and ask the same questions (note; one caller screened himself out when he said he didn't want to get out of his car and walk the five feet over to the sign!).