be able to offer a service which is for people to register domains with you're own regitrar usually expensive to have a reseller website
Since you posted it in Domains Forum so I assume you are talking about Domain Reseller. Domain Reseller is a kind ofaccount through which you can sell domain names. There are many Domain Resellers but they all need you to add some funds through which the customers can order domain names from your Website. The best part is that you can decide your prices and your renewal prices but almost all domain Reseller accounts are very costly. I personally user Reseller Club domain reseller account which costed me $499 in deposit which Ican use for domains further. However through this account I can have customers as well as Resellers under my Reseller account. Other Domain resellers are : Enom Godaddy NameCheap etc. But if you are talking about Web Hosting Reseller Account then it is also almost similar to Domain Reseller Account, You rent one web reseller account, make some Packages from your allocated space and bandwidth and then resell them through your website. There areother option than beingreseller also like Master Reseller (Which can create Reseller too, Alpha Reseller (Which can create Master Reseller & Reseller ) VPS, Dedicated Server etc.)
Reseller hosting is a form of web hosting wherein the account owner has the ability to use his/her allotted hard drive space and bandwidth to host websites on behalf of third parties. The reseller purchases the host's services wholesale and then sells them to customers for a profit. A certain portion of hard drive and bandwidth is allocated to the reseller account.