Best way to find quality leads?

I own a small web design firm and I’m looking for the best way to pay people for quality leads that turn into sales. I’ve thought about an affiliate program but where the prices of everything is different. based on the job I don’t have a set price for products to sell directly on my site so I’m not sure if an affiliate program would work.

I have tried Facebook ads for leads and they have yet to return anything but spam. Currently trying linkedin and reddit.

Google ads are way too expensive at $10-$22 cpc. I would be willing to pay that if it resulted in a sale.

Im willing to pay up to 20% of project total or $50 whichever is more for each new client that converts into a paying customer.