We all have budgets for our own reasons -- few of us are rich enough to simply waste money, so knowing the limits and trade-offs is a good thing. $150-200 to get a GOOD trainer in flying condition is actually pretty reasonable. You can go cheaper, but corners will need to be cut, whether it be in ease of setup, the reusability of the support gear, friendliness of the trainer, survivability in a crash . . . This is what you pay more for.
Starting out with your chosen radio, a BNF version of the full Radian will get you learning on a large stable platform that can take a hard landing, and swapping your Rx for the one built in (be prepared to carve out space for your Rx), your radio gear can be used so you get comfortable with it. Trust me, when your build completes, you'll probably still pull out the radian to fly from time to time -- she's that much of a sweetheart.
Going with a RTF version of the UMX radian is a decent runner-up. You won't be able to reuse the batteries in your new build, and you'll learn on a "toy" transmitter -- looks and feels more like a game controller, has no programmability, and the range is poor -- instead of the nicer radios you have. It's still a great plane to fly, so you'll probably fly it from time to time as well. The problem with this option . . . I can't see anyone selling a RTF version of the UMX radian anymore. The BNF version assume you have a DSMX or DSM2 radio to bind with it . . . So you'll need to add on the cost of a new Spektrum compatible radio to go with it
Trimming the budget further can be done if you build your trainer as well -- the two I've mentioned can be built and outfitted with your radio gear in about a week's worth of evenings for $50-75, and can be completely rebuilt after a nasty crash for a small fraction of that. There is some merit to the argument that it's better to buy your first trainer, trimmed and ready to fly, instead of building your first trainer . . . But after each build, each repair becomes easier.
Your plane, your call.