It is well worth it to spend as much as you possible can ( or save ) for a good TX.

If you get the right one, you will not be buying another TX for a LONG time as it can handle all of your planes and needs.

I advise people to jump right up to 7+ channel 2.4gHz TX's as these typically have tons of features and the mixing alone will save you a bundle on things you do not have to purchase.

You may have "only" two planes now, but what happens when that turns to 10+?

Then in hindsite the purchase of a good TX will seem like a very good idea.