(Note: this is a work in progess, and may not be updated at all times. All prices, contracts and agreements should be verified before planning starts.)
Becoming a registrar consists of a number of steps, and costs a few thousand dollars. In addition it will be required of you to fill out some paperwork, perform technical accreditation tests, and describe your business plan. The exact work you need to do will depend on which TLD(s) you wish to register domains under. On this page I will outline broadly how you become a registrar, with focus on gTLDs.
If the process sounds expensive, time consuming or difficult, you should consider a reseller solution instead. This costs a fraction of the price, can be instantly available, and there are usually options for all levels of expertise and integration, from a click-to-create webshop to API reseller solutions. (HINT: you can get started today on www.GoDaddy.com)
To be a registrar on one or more gTLDs, you must first become an ICANN accredited registrar. Last verified in November 2009, this will cost a few thousand dollars. ICANN publishes a list of "Financial considerations" here, and as of this writing it will amount to a minimum of USD 6500, where USD 2500 is the application fee, and USD 4000 is a yearly accreditation fee. You will note that the USD 2500 application handling fee is non-refundable, so if you bungle your application, you will lose USD 2500 and you will not become accredited. If you want to be a registrar for more than one gTLD, you must add USD 500 per additional gTLD.
You must also demonstrate to ICANN that you have USD 70,000 in working capital, and insurance coverage of at least USD 500,000.
To become accredited to do registrations on the .NAME gTLD, you will need to contact Verisign. They have made an overview of the process available here. For the technical accreditation, you will most likely want to use epp-rtk, the EPP Registry/Registrar toolkit. This is basically an SDK that will allow you to develop an application that speaks EPP. You will also need an XML library like xerces for whichever language you choose to use, and domtools, which is also downloadable from the epp-rtk site. If this all sounds like a too daunting task, watch out for an open source registrar.
.NAME requires ICANN accreditation.
The registry operating the .COM and .NET gTLDs is Verisign GRS. They have an informative website, detailing the steps to become a registrar quite well. Information on these steps can be found here. Rather than using EPP to receive registrations, .COM and .NET use the older RRP. This is a line based protocol that is simpler to implement. There is also an open source toolkit for .COM and .NET, which can be downloaded here.
.COM and .NET require ICANN accreditation.
Neustar is the registry responsible for running the .BIZ gTLD. If you wish to sell .BIZ domains, go here. To my knowledge, the .BIZ registry uses EPP for registrations, like .NAME. However, they seem to call it XRP on their website. See the epp-rtk and libraries under the .NAME section above.
.BIZ requires ICANN accreditation.
.INFO is run by Afilias. Details are listed here. .INFO uses EPP for registrations, see the .NAME section above for details.
.INFO requires ICANN accreditation.
.ORG is run by the Public Interest Registry . Details are listed here. .ORG uses EPP for registrations, see the .NAME section above for details.
.ORG requires ICANN accreditation.
.NO is run by NORID. Details of what needs to be done to accredit with NORID can be found here It costs NOK5000 to become a registrar for .NO, and they take a NOK5000 deposit as well. They accept registrations over email using a template that must be filled in. It should also be noted that currently, anyone wishing to register a domain on .NO needs to have a norwegian organisation number, and can then register up to a maximum of 15 domain names.
.NO does not require ICANN accreditation.
Don't spend all that time becoming a registrar. It's not worth it. I'd recommend you sign up as a reseller (or even affiliate) on www.GoDaddy.com to earn money on sales through their technical solution, rather than building one yourself. Prices to get started are laughably low compared to building anything yourself, and a reseller solutions can be up and running almost immediately.
Being a www.GoDaddy.com reseller gives you a smaller margin than being a registrar, but the significantly smaller costs and investment more than make up for this. After trying your strategy on the real market for a while, it is still possible to become a registrar when you have acquired the necessary experience.
Becoming a reseller does not require ICANN accreditation.
(C) Ketil Froyn, 2004, 2009
Note: It doesn't help for maintaining a page like this when websites change links, and don't set up the appropriate redirects. Seems ICANN and Verisign are the winners, with Neustar/Neulevel, Afilias and Norid blundering blindly about in the battle against link rot.