I want a model

Monogram is a good place to start for low priced kits of fair quality.

Try doing a search on Ebay for Tamiya and/or Hasegawa. I've found some nice models on Ebay and they're usually a lot cheaper than the hobbyshop. These two manufacturers produce high quality kits in every genre. They run a little high at the store but you might luck out at an auction.

You might also want to check out http://www.modelexpo-online.com/default.htm
sometimes they run sales/clearance on their kits.

-fish

If you use Ebay look for WWII 1/48 scale kits by Arii/Otaki. You can almost always get them for less then $10.00 and though their cockpits are a bit sparse, they're pretty good for shape and finely engraved surface detail.

with quality vs price in mind you cannot beat Italeri.
I have a 48th ME262 in a box that looks great.
Also Hasegawa kits are not as expensive as they used to be.

I agree with Aurora on Otaki/ARII products... They're the best example for value for money kits... Surprisingly their 1/48 Non Japanese aircraft(ie Allied and Luftwaffe aircraft) are of much better quality than their Japanese planes like the A6M Zero... They are hard to find nowadays but Ebay should be a good place for them!

Cheers,
Nandakumar

Italeri makes a nice P-51B in 1/72 scale. I think it costs $9.00. The cockpit detail isn't all that great, but the canopy is small and dark so you can't see much.