I will share how I go about that situation, maybe it will help you.
Consider creating an all in one package, thougha small investment would be required, but if you charge enough for the site, it should pay for itself.
First you can open up a hosting reseller account, I use to companies, some are very inexpensive, 20 bucks a month.
You can also sign up as a domain reseller with wild west domains or enom, once again there is an investment, but if you do enough sites, this should pay off.
Combine these with your site design and you can offer your clients an all-in-one solution. You can register the domain for them and host the site you create for them.
You cover the initial costs per client and bill them to get reimbursed.
Just my view, hope it helps.
~~ Joe V aka Puterman