I guess we'd all like to do that, but in reality just about everyone collects some stuff that becomes obsolete. Take the radio for example, We were assuming that buying a nice radio up front that will serve you for a couple of years, might save you money in the long run but in actual fact it won't.
If you were to get a basic 4 channel radio, for example a Futaba 4YF, it would cost $129.99. A Futaba 4 channel air pack costs $114.99 plus $12.99 for the receiver crystal giving a total cost of $127.98. This means that the transmitter only cost you $2 !! So, you could defer the cost of a better radio to when you get a second plane, then you'd also have a spare transmitter or a buddy box!

You do have a point with the RTF trainers though, especially with the Superstar and Avistar. Buying the components would cost $129.99, $99.99 & $54.99, total $284.97 against the package price of $279.99. Really you'd want to buy a decent engine, so the main saving is the cost of the engine, but that needs to be compared to the cost of buying the tools to assemble an ARF.

If you're going to train at an AMA club (the recommended option) then you'll probably find you won't want a co-pilot. If you do a search on the Nexstar for example, you'll find that most people disconnect the AFS.
I could ramble on more, but that'll do for now...