How about an 8 channel 72mHz radio for the price of a 4ch?

One that:

- Is computer controlled
- Provides Exponential / Dual Rates / End point adjustment / servo reversing / etc. etc. etc.
- 7 active mixes
- 8 channel output ( works with your 4 channel setup )
- Can transmit on ANY 72mHz channel ( synth frequency )
- Has a built in channel scanner to find used/unused channels & for safety.
- 99 model memory ( can control up to 99 DIFFERENT planes )
- Is shift selectable ( can control Futaba, Airtronix, Hitec, JR, etc receivers ! )
- Comes with an 8 channel receiver ( which will work in your 4 ch setup ) that can receive on any 72mHz channel or shift
- Comes with a High quality servo, battery pack, switch, etc.
- NO CRYSTALS
- 1024 STICK RESOLUTION
- TRIM & RATE MEMORY ( remembers the trim setting for EACH model )
- AILERON DIFFERENTIAL
- FLAPERONS & ELEVONS
- V-TAIL
- MODE 1 OR 2
- COUNT DOWN TIMER
- LOW TX BATTERY WARNING
- EASY PROGRAMMING W/LCD DISPLAY
- AJUSTABLE STICKS (TENSION/LENGTH)
- 40 MGHZ COMPUTER CHIP


And costs $140.00

Even if you later switch to 2.4gHz the above will be useful to fly foamies, RTF's and other planes that you may acquire.

Check it out:

[link=http://www.polkshobby.com/index1.html]Click me![/link]

I picked one up to control my fleet of RTF foamies, and find it to be a great first TX combo.