aaron_ginn,
I'd like to make some suggestions / statements.
#1, TCH has been my best investment for my business. I currently use the Silver Plan myself. Also, if you're going to offer downloads or streaming of any type you might want to look into the gold plan or above since downloads use bandwidth.
#2, I'm using oscommerce (www.dancefloordj.com) and its been great, but it took me a LONG time to get it where I wanted it.
#3, Write down on paper, what you want your site to look like and do. This pre-planning makes customization OSC a TON easier.
#4, Do some research on Chain Reaction OsCommerce and OsCommerce Max. They already include many useful contributions.
Yes, you do need SOME kind of merchant account. BUT WAIT... there is a FREE OPTION (well free startup anyways)
PayPal Now accepts credit cards even if the customer doesnt have a paypal account. OSC can combine Paypal via the OSC PayPal IPN Contribution Search their site about it.
I also Process Credit Cards offline with ProPay.com Only $35 a year and I think it's only a 3%+$0.35 per transaction charge.
Currently, OSC has SEVERAL contributions / modules for several merchant gateways. Do some research which will be best for you.
Purchasing an registered SSL Cert from TCH is MUCH easier in OSC than the free one.
I've been using OSC for over a year now and have 2 sites using it. It's great if you want to spend the time to personalize it to your need, sucks if you're time constrained. Feel free to contact any questions and I'll try to help out.
Also, OSC has a helpful msg board. forums.oscommerce.com
Peace