Need Advice: Payment processing MULTIPLE websites

Hi, I'm hoping someone on here has experienced the same or similar problem and they can help me with a solution.

I own 100's of domains and many of them have developed websites on them to collect ad revenue and affiliate commissions. However, recently I've been looking at other ways to monetize a number of websites/domains and I'll be experimenting with various strategies from micropayments to donations.

Here lies my main problem. I have one PayPal account and one bank account.
I need to find a way to accept payments from various unconnected websites each with their own branding. I know some people set up a 'head Quarters' type of set up with paypal where all different sites they own go through this 'Head Quarters' for payment processing. Personally, I don't like this set up because it can be confusing for a customer.

Basically, I need each website to have brand continuity when going through a payment processor (Logo, invoice, email etc, etc) but I need to process many different websites via one account.

I expect I will have to find an alternative to PayPal for something like this but I would prefer to use PayPal if possible.

Has anyone here experienced a similar problem? How did you overcome it?

BTW - Processing payments locally on each site isn't an option for me because that would require the added expense of buying an SSL Certificate for each website. (This would make it an expensive experiment.) So, please bare this in mind, cost is definily an issue for me. I guess I could afford a solution that had a small monthly payment to process every website but I couldn't afford this individually for each website.

Hope this all makes sense. Sorry if I've made it sound complicated.