Advertise on social media or go on Craigslists and post an Ad to let people know what you are doing. I find it best to connect with other investors by going to meet ups in your city or if you have a Facebook join real estate investment groups that are strictly for your city and be active in those groups. Those Facebook groups are huge for finding investors and networking because Flippers are looking for people in those groups so they can find more deals.
If you want to spend some money what you can do is send direct mailers to investors letting them know that you are a wholesaler. you can use the website listsource.com to find buyers and when you get their information you can send them mailers by using click2mail.com.
To find out how to use list source to find buyers you can search on youtube [find buyers on list source] there should be alot of good videos to walk you through it.
I hope this helps you and good luck on your wholesaling business!