Need improved gas mileage

This summer I was thinking about investing in a cold air intake. I don't know much about automobiles and usually leave much of the stuff up to my dad, but I was wondering what brand would you recommend for a cold air intake? The only brand I recognize is K&N, but as I said before I don't know much. I would imagine they are all relatively the same in performance, but I noticed some price difference. Please let me know. Thank you.

Car: 2000 Toyota Tundra, V8 4.7L

They are all relatively the same for performance - no improvement documented. Save your money. Exhaust improvements are more profitable and actually do something for performance and mileage. You can also go for a TRD or AMSOIL air filter. They are high quality and do much more than the cold-air intakes. They won't increase your mileage, but they will give you hp.

Could you direct me to a site that has these air filters.
Also, what would you recommend for exhaust? I think I would like to have it cut off so it wouldnt show. Probably would like to spend $300-$600 on it. Let me know, thanks.

https://www.amsoil.com

or

http://www.trdusa.com

For exhaust mods, I would go with a cat-back system from TRD or other reputable manufacturer (search these forums) or headers plus a custom exhaust if you want to spend some additional cash, but really want some improvement. You can use one of the quality cat-back systems as a basis for your custom exhaust, just couple up a high-flow cat converter to your headers and join it to a cat-back system.

How would I benefit more from an air filter than cold air intake? I will probably get exhaust sometime next year, but for the time being would an air filter and cold air intake noticeably improve my performance?

Also, what do you think about Throttle Body Spacers or Helix Power Tower?
http://www.performanceproducts.com/CategoryPage.aspx?category=Performance+Upgrades&subCategory=Air+Intake%2c+Turbos%2c+Superchargers% 2c+%26+Throttle+Bodies&subCatID=212&cid=17#product

How would I benefit more from an air filter than cold air intake? I will probably get exhaust sometime next year, but for the time being would an air filter and cold air intake noticeably improve my performance?

The filter (TRD or AMSOIL) is much more efficient than most any others, both in particle size and airflow. Better performance.

Cold air intake limits your choices of filters. You are better off with an excellent filter and the factory intake than the other way around. You can improve the efficiency of the factory intake system also.

Again, improvements in the intake won't help your gas mileage. Only adds power. Letting more air in just permits your engine to use more gas. The more gas, the more power at any particular throttle setting. Cruising at 60 mph will require less throttle opening, so it all averages out. More gas, less throttle. The exhaust improvements actually make your engine more efficient and improves mileage.

Also, what do you think about Throttle Body Spacers or Helix Power Tower?
http://www.performanceproducts.com/CategoryPage.aspx?category=Performance+Upgrades&subCategory=Air+Intake%2c+Turbos%2c+Superchargers% 2c+%26+Throttle+Bodies&subCatID=212&cid=17#product

I have a very low opinion of both of them.

I have a very low opinion of both of them.

In that they don't work or just a waste of money?

Both

Intake manifolds on many engines are heated to improve economy. Hot air is less dense therefor less fuel (leaner mixture) is needed for the same volume of air.