I know you think you can't take the engine out of your Super Sportster. But that's simply not the case. Pull the engine out of that plane and put it on your trainer until you are finished flying the trainer, and then transfer it back to your Sportster. Engines normally survive crashes, so I wouldn't worrry about it being destroyed. However, even it is destroyed it's an evolution engine. These aren't rare engines and are very easy to replace.

That would save you $75. Buy the receiver as it's not a throw-away item either. You'll be able to use it later on down the road in other planes.

Since you are limited on cash you would be better off flying your trainer. Park flyers won't handle the bumps and bangs associated with learning to fly as well as your trainer will. So the chances of losing your money by damaging the park flyer are higher than with your trainer.

As others have said above, your trainer will more than likely fly just fine. And if there are some issues with it they should be fairly easy to fix in order to get your trainer flying.

Ken