I need to stay at a hotel close to CDG and find that they are quite pricey - $300-$400. I would rather not pay that high a tariff.

On the other hand, I have twice chosen cheap hotels near airports, one at Nice and one at Gatwick, and they were so awful, that I could not sleep and could not wait to get out of them!

Any suggestions?

bid on priceline.com for a 4 star and you will be happy. or take a look at www.hotwire.com. there might be a 4 star there for what you would like to pay.

I have stayed at 4 stars and stars there with no problem.

meant to say "2" stars.

I booked the Sofitel directly via Accor, almost last minute. It was a very nice hotel, very comfy beds, breakfast included, shuttle to CDG. I paid 125 euro

www.booking.com shows five dozen hotels in the vicinity of CdG. Filtering for those over 200€ turns up 10 to choose from, and lots more at cheaper levels It's impossible to give closer price estimates since you did not indicate when you are travelling.
Be careful that the official star ratings in France do not necessarily match the stars imposed by booking.com, priceline or the other booking agencies.
I endorse checking the huge Accor chain of hotels with brands at various price points at or near CdG. Its free shuttle vans run a circuit among these hotels that is very convenient. http://www.accorhotels.com/gb/booking/hotels-list.shtml
Just be sure the one you choose is not further out, such as those aimed at the nearby convention centre.

I'd also suggest Priceline as you can get good deals. I got comped once at CDG at the Hilton and it was really nice. If you don't want to bid, use www.booking.com for a set rate, you can get 4* CDG hotels for around 150 euro or less. the 4* Millenium with free shuttle is only around 110 euro.

Yes Accor Hotels is your answer to much cheaper hotels in the vicinity of CDG and linked by shuttles to terminals. www.accorhotels.com - and a friend just stayed in a Novotel there and she nearly missed her flight when the shuttle bus was late and took longer than expected so caveat emptor about that.

You'll find several hotels right at the airport and at least half a dozen more within a mile (all with shuttles). The Ibis, which is right at the airport, is a simple hotel but should cost less than 100 euros, but if you can get a room at a nearby Sofitel for 125 euros, I'd jump on that. Booking.com shows several different hotels near the airport with shuttles, all for 125 euros or less, so this may be a timing issue, or you may be checking only the upscale hotels.