Any helpful tips on Unlock or Versa Lok retaining wall blocks?

I'm a amateur landscaper & have my own small business. I have a client who has asked if I can use Versa Lok retaining wall blocks for his property. He's willing to pay more & all that. I'm completely good with using them but the research I have done. It shows that you need to be in good with a dealer to have access to these blocks. I told my client that I would look into speaking with the dealerships & work on getting access to these. My question to you guys. Is..... You guessed it. Which ones have you guys worked with? Are they're any alternatives to Versa Lok & ETC. If you have worked with any of these certain blocks which company do you guys prefer? I appreciate any insights y'all. Austin W/ Taylor made Landscaping.