I can't seem to get to the direct booking to any of the trains that go there, just booking agents that according to the net are not reliable? Help!
I suggest that you fly on a budget airline. Vueling and easyJet fly MAD-CDG. Tickets on Ryanair are often the cheapest, but you'll fly into BVA (Beauvais) which is a 90-minute bus ride from Paris. Pay strict attention to check-in deadlines. If you miss the deadline, your ticket will be worthless. Also pay attention to baggage size and weight limits. You'll pay extra if you exceed them. Ryanair's fees for doing so are quite high.
There aren't many trains between the two cities and I believe the most common is an overnight. The standard answer is to fly. In addition to the dicount airlines, you can also try main ones in and out of the main airports. You might find them nearly as competative in price with less transit hassle.