Yeah, you have to be buying components in large quantity to get them fairly affordably. You get get the sensors and STM chips off aliexpress way cheaper than from digikey/mouser/element14...but...who knows what the quality will be. Sparky2 would be tricky to hand solder, could be done in a toaster oven fairly easily...but wouldn't be a great first project with that size of parts. I still need to finish some re-work on the submicrolrs RX I did in my old toaster oven. Just have to replace one cap I lost and reposition the crystal...but with 6 contact points the crystal is a bit tricky to do without a good hot air station. I've done these things with a $7 embossing gun from the fabric store - but it's tricky because it blows more air than a real re-work station so tends to blow components off if you're not super careful/patient.