First of all, even the delivery of a message is worth a payment. The Bible is clear that, “The worker deserves his wage.” (I Timothy 5:18) Often, churches, too, do not bless people financially for their work in a way that is appropriate. Ramsey is providing a service; it deserves payment.
Christians are people with a need for advice, be it medical, in the form of a trade, financial, etc. Providing this service in a church setting is no different than a Christian going to a financial advisor for advice. I perceive the fact that it is being brought into the church as a blessing — as it is a necessity in that arena just as it is needed in others.
In fact, I have witnessed Christians who make many financially unwise decisions. I have worked with people in the ministry that did not know how to manage their money. Maybe some of these individuals would not even seek out help if it wasn’t brought into their church — much like I bring parenting classes into the local church for that very reason, because being Christian does not make you wise in all areas. In fact, it can often be a cop-out to not do things with excellence, as we are supposed to.