What does "affordable" mean to you? What's your price range? Hotels in Paris are in general very expensive.
Are you planning to go into Paris itself for a brief visit or just go right to the hotel until your flight the next morning?
8:30 isn't necessarily that early when catching a flight within France. If you are planning to go into Paris anyway you could get a hotel there and just take the Roissybus or RER train (depending on where you will stay, one may be more convenient than another) and get back to the airport by say 7:00.
You can also try Priceline.com's "Name Your Own Price" service and choose the CDG airport zone. I see on the BetterBidding site that some people have recently won ($74/night) the Sheraton at CDG which is IN the airport (I stayed there a few years ago) and couldn't really be more convenient for an airport flight, as you just walk from the hotel to the terminal. You can't be guaranteed ANY hotel when bidding with Priceline, however. There's some chance you would get a different airport hotel, perhaps even one without a free airport shuttle, so you are sort of taking a chance in exchange for possibly getting a perfect hotel at a great price. You can see what people have gotten recently on Priceline by searching BetterBidding for "Paris."