Hi HashenD,
In my opinion, it's a tricky decision to make as hosing with an unlimited package has a risk of being damaging to your websites SEO (if you have one or will have one)
Personally, there are some great deals out there for unlimited hosting packages. And I feel that the cost, ease of use, and service for hosting and maintaining client sites far outweigh the slim chance of negatives affecting your personal / business site.
With an unlimited package, you can easily transfer a clients domain name (if they have one) for a small fee and begin hosting it. Additionally, you can add more domains and web roots right onto your unlimited hosting account for new clients. It makes those "new web deign clients" faster and easier to manage in my experience.
When it comes to billing, your cheapest options are Paypal, Google checkout, and an ecomerce plugin trough a Wordpress theme. Something like
Woocomerce may all be viable options for you.
I hope this has response helped you in some way.
Joe.