Follow Dave's advice with the receiver, when they are so cheap there isn't much point in building your own.
Your original circuit used 30MHz although I'm not sure why you chose that frequency. It lies on the border of short waves and VHF so a suitable receiver would be difficult to find. If you change to 90MHZ it falls in the domestic VHF broadcast band so receivers are plentiful.
The schematic you show in post #3 might work but it is likely to be unpredictable in operation. There are several reasons but the main one is the frequency is decided only by the tuning coil. The coil isn't just the curly 'turns', it includes the wires at each end of it and one end is the battery wire. It follows that the length of battery wire changes the frequency - not a clever idea!
There are ways to fix the problems but all will make it considerably more complicated. You also have to be very careful with the component layout and wiring lengths as you work at higher frequencies so your construction techniques become very important. I suggest you stay with the 90MHz idea but look for a design (plenty on the internet) that includes a component layout and in particular look for one that does not connect the antenna directly to the tuning circuit. There should be at least one transistor amplifier stage between the source of the 90MHz (the oscillator stage) and the place the antenna connects to, otherwise you will find the antenna length and things moving nearby to it will make the frequency drift.
Brian.