I've started a home based eBay consignment service along with basic computer repairs. I'd like to be able to accept credit/debit card payments from my customers and would like to use my site for this purpose.

I'm leaning towards using Host Gator as the host for my site which I see offers Shared SSL.

For my needs, no one will be coming to my site and purchasing a good or service, I'll be billing them externally and would just like to be able to process the charges through the site.

What will I need in addition to the SSL cert to be able to pull this off?

I'm completely new to e-commerce so anything you can offer will be of great help. Thanks!

You need a good billing program to take care of your billing and credit card charges and you will need a payment processor with a Merchant Gateway such as Authorize.net, etc. Even a good accounting package such as Quickbooks can be used to do billing and charge credit cards. Or you can use the Virtual Terminal that comes with most payment processors to manually charge credit cards. I hope this helps!

For my needs, no one will be coming to my site and purchasing a good or service, I'll be billing them externally and would just like to be able to process the charges through the site.

Not sure what you mean by processing them "through the site." But, if you're not collecting billing information via your site - which I think you're saying - then don't even deal with processing through your site. The less layers of handshaking between entities, the better. If you're just wanting to manually process the orders, then just get any merchant account that has a virtual terminal, as noted earlier. All you need with a vitual terminal (besides their software) is a connection to the internet. That's it. Can be dialup, or whatever. Processing cards real-time adds additional "gateway" charges that I don't think you need or want to pay.

if its ebay business i guess its better be with their paypal, they much easen your job if you do paypal with ebay as they are one company !
Ofcourse having a merchant account as you are adviced or asking is the best for processing , but you specifyin ebay is what makes me advice you with paypal

If you are using eBay, you may want to consider a merchant provider who is a reseller for the PaymentClearing/iTransact gateway. It has a nice built-in eBay module that you could use to send a customer a link for them to make the payments to you very conveniently.

However, at the most basic level, all you really need is a merchant account & gateway. You could even utilize the secure server order form capability provided by some gateways and avoid having to have your own SSL certificate if the gateway you use supports that.

A lot of people use Paypal for ebay. This is especially good becuase Paypal is integrated into the eBay system.