As reminder, using CloudFlare already reduce our privacy. I also recall theymos would change if there's other technology or service which isn't far more expensive than CloudFlare.
I definitely don't think the cost would be a huge factor, when comparing cost and benefits. There are solutions that are far more expensive than CloudFlare but doesn't perform much better. Generally, if you compare enterprise solutions and CloudFlare's $250/month, you're probably going to face similar problems.
This challenge only comes up when you're using known Tor/Proxy IPs which is usually where DDOS attacks originate from. In terms of L7 attacks, the challenge is what limits its effectiveness before it hits your site. When facing large DDOS attacks or sophisticated ones, you don't have many good options beyond CloudFlare. Privacy is compromised eitherways when traffic has to go through someone else before you.