Adding a new payment gateway to CBSubs

Primarily, I need single transaction (lifetime subscriptions) amounts as high as ~ $2,000.00 USD, where they state a mazimum transaction amount of $99.00 - are you saying that that maximum transaction limit can be bypassed?

That's a soft limit. It's done to avoid abuse and liability issues. You need to contact them to have the limit increased, which they absolutely can do; normally this is just an email, phone call, fax, or rarely a hand written letter requesting an increase.

Having communicated with them in several emails, I was told the most they could increase it to was $200, and that would be with 6 months history with them... I hope to be selling several of those lifetime subscriptions in the first 6 months, which is 20 times (10 if I got the increase) the limit. And aside from the lifetime, yearly subscriptions would be as much as $750 for some plans... again beyond the limit (or what they have said they would increase it to).

I spent a month communicating with CCBill before I gave up on them; I had assumed they would be my processor, until this problem came up. I am now talking to dozens, but so far haven't found any which fulfill my needs whom I feel would be reliable...

There's not much you can do about that. They're not going to allow $2,000 to go through their gateway when they have no clue who you are and with no history with you. All the liability is on their shoulders. You're going to have an extremely hard time finding a reputable gateway that's going to do this. If you find a gateway that will you should be extremely cautious, most smart gateways won't touch your needs with a 10 foot pole (it's a huge risk for them).

Here's what I suggest. Use CCBill for standard durations that don't have such high cost. Then use Offline payment gateway for the lifetime plans or plans with large amounts. For the Offline gateway you can provide them instructions to wire transfer the money to your bank account and completely bypass needing a gateway or you could provide instructions for sending cash or check. This puts all the liability on you, but there's really no workaround as most gateways aren't going to take the liability for such large transactions involving adult content.