You can check into vehicles on Kelly Blue Book (KBB.Com) and Emunds.com, also Consumer Reports.org.
There are many sites on the net that allow you to compare car prices. One site that compares BMW versus Audi Models is Thecarconnection. Another site is Paultan.
If you want to compare models, look for an independent treadmill review site instead of the manufacturer's site. Try TheFitnessOfficial.com or TreadmillTalk.com to compare over a 100 models and many brands, including cost and feature comparisons. There are several web sites that will allow you to compare prices and features of treadmills. I would suggest checking out Amazon.com for great prices and real world reviews.
CheckAutoParts.com
Edmunds specializes in selling cars of all different makes, years, and models. Find the car of your dreams on Edmunds site at a very good deal. One could also compare other prices of specified cars.
Look up each model on a site like best buy or Wal-Mart. After finding the models, you should see a list of features and you can compare them each yourselves or compare them on the sites.
You can compare prices and models before purchase at most cell phone sites such as AT&T, Verizon, Vonage, Sprint, cell phone shop, accessory geeks, cellular factory and discount cell.
C Net is a worthwhile location to search for television reviews. They compare different makes, models, brands, and sizes to help you find the best one. They can be found here: http://reviews.cnet.com/TV-buying-guide/
You can choose up to four different models to compare at a time at http://www.cars.com/go/compare/index.jsp . It compares things like: MSRP (when new), available engines and transmissions, crash test data, etc.
You can buy them from Walmart,Target,Sam's Club,Buy.com,this site (FreshDeals.com) and so forth.Richmond makes very nice models.
I would say the best site for reviews and comparing models for plasma televisions would be Wal-Mart or best buy. They are two great sites with lots of products.
Many online sites have wireless router charts to compare models. One such site is the Best Buy website. They have many different routers and you can compare them with others.
Onkyo makes many models of receivers. Go to the Onkyo USA site to learn which of their receivers will suit you best, and then click the button labled "Online Dealers" to find the dealer where you can order your receiver. Compare prices from several dealers if cost is important to you.