Hey,
I'm on the development team for salesorder.com - an affordable, easy to use and deploy small business erp (CRM+Accounting).
I'm seriously thinking about providing integration between our web application and WHMCS. Having looked at the challenge and I estimate this to be about 5 weeks work to develop, test and bring into service.
Obviously I want to qualify if there is a market for this back end solution to WHMCS, before I cut any code.
So If this is the solution you need, then please leave me a message here and I'll reach out to you as and when I have made some progress.
Cheers
Nick