Here are some things you can do with enom....
1. Open your own reseller account with them and pay the advance amount to establish it at whichever of the tiered prices they offer. This information and how to do it is displayed at their web site.
2. Find a reseller who is prepared to provide you with a 'reseller' account under terms and conditions which may be easier and less expensive than dealing with enom directly, that is to say they may allow the minimum purchase of one domain at a time. Note that the minimum amount that you can add to your reseller account is US$25 by credit card. You will now be charged another 3% on top by enom for CC account refills.
3. If you use Registry Rocket with either the direct enom, or the sub reseller arrangement, you get to use the bundled merchant services provided by enom.
This means that when a customer visits the page set up for your Registry Rocket account and they choose to pay by credit card, the payment is processed via enom's merchant service. The 'profit' you earn has 3% and 95 cents deducted by enom, plus the amount you pay for domains, and the balance is placed in a 'commission account' where it cools for 90 days to make sure it's not fraudulent. After 90 days, subject to the total, you can either have them send you a cheque, or you can transfer the amount to your main account where you can register domains and purchase services manually, even with the registry Rocket link on your web site.
This is the only way the Registry Rocket works, but at all times you can also access all the enom services manually.
4. If you choose to use the API which works with .asp or Perl, then you can use either the enom merchant service as with the Registry Rocket, OR you can code in your own merchant gateway, eg authorize.net. This means that the customer accesses your merchant account directly from the enom API when a purchase is made. To do this you must have a credit balance in your reseller account because the process doesn't split the customer payment between enom to pay for the domain and you to deliver your profit.
If you use the enom merchant account this problem does not arise because they take the domain payment and merchant fees from the charge and credit the 'profit' to you.
So, if you use the API with your own merchant gateway [I don't think the 2checkout type of service works, you must legally be the merchant] then you must put cash into your account to fund the purchase and you receive all the proceeds from the sale.
If you use enoms merchant service you don't have to have any funds in your account.
If you use the API, Chicken is right, you must have your own SSL certificate and the Net:
SL module for it to work.
5. you can at all times just regsiter domains manually by filling your account with enough money for 2-3 domains, once it's established
6. You can create sub accounts for your customers to hold their domains in if you wish, but your access to those is restricted if you don't have the password.
The number of features that are standard with enom is without fail the most you can get from any registrar and it's free.. you can even get domains for $6.00 if you don't require any DNS... eg if just hoarding a name/s.
The API requires that someone with some basic knowledge of scripting language installs it, it isn't point an click.
consul is probably right about how to handle small numbers of registrations, but with enom you can do this with the help of an existing reseller who will give you the one at a time option.
By the way this is not an ad for us, as we are obviously enom resellers, because we don't give out sub reseller accounts to anyone other than our own existing customers and that's by private treaty.
If you are looking for some enom resellers who might help you, consider asking enom, they are very nice people and 'should' have no problem with suggestions, as far as I know. [hoping I haven't put my foot in my mouth]
Hope this helps..