Priceline is your friend for rental cars and hotels.
Make sure you pick at least a 4 star hotel though as sometimes their ratings are less than what you expect them to be. While a three star maybe fine, the three star you get may not!
As for Priceline and cars, pick exactly what you want and don't *upgrade* at the counter as the price can and most of the time will skyrocket. So if you don't want a compact car, don't request it on Priceline.
As for tickets, there are several ways to get them. A reputable way is the preferred way as your tickets won't be rejected at the game if you know what I mean.
What I mean by reputable ticket seller is one time we purchased Texas Rangers tickets on Ebay and the guy sent us the actual ticket. What he did though was resell the tickets for a better price and use the "Email the ticket" option which invalidated the phyical tickets he sent us. While he did refund the money to us, it wasn't pleasent being rejected at the gate. We had the option to purchase other tickets, at a Cowboys game you may not have that option. If you are flying down to Texas and getting a hotel, I don't think you want to miss the game because of some dirt bag screwed you over on the tickets.
For flights, just discount and last minute ticket places on the net. Sometimes the big places like Expedia are the cheapest. My wife is really good at finding great ticket prices, and many times Expedia is it. Sometimes they cost a little more than maybe one other place, but there is also a service level you get with a place like Expedia vs JohnsDiscountAirFair.com
