I have an Apprentice S myself and am just using the DX5e that came with it. I'm just going to buy a new Tx when I get my next plane, keeping the DX5 on the Apprentice for teaching others, when my skill gets that far. I've heard several folks say they made a deal with their LHS where they took the DX5e out of the Apprentice box, knocked the price a little, and then bought a DX6 or better along with it. It would be worth talking to your LHS to see if they'd do something similar.
Another alternative.... You could get a receiver-ready Sensei:
http://secure.hobbyzone.com/flyzone/FLZA3014.html
Then add a Tx/Rx combo (or buy them separate). Something like one of these:
http://secure.hobbyzone.com/radiosan...s/SPM7800.html
http://secure.hobbyzone.com/radiosan.../FUTK6900.html
http://secure.hobbyzone.com/radiosan.../TACJ2600.html
A suggestion I have on choosing a Tx/Rx (if you haven't already decided on a brand) ... if you're thinking about joining a club, see what brands they use. If they're all primarily using one brand, I'd go with that brand as they'll be able to help you get it setup a little easier.