When starting the minimalistic APRS transponder project the goal was to make a semi-disposable APRS transponder costing less than 28 Euro (~35USD).
After spending many nights designing a VHF transmitter from cheap easily obtainable parts the price landed around (for the transmitter) 13.5 Euro (16.75 USD). This was not including about 1 hour of assembly time. All seem good but then I found this module on the Internet for 11.12 Euro, including shipping. Not only was it cheaper than I could ever build something myself but it was also a fully programmable VHF tranceiver and had 1W output.
I have now decided to base my APRS tranceiver around this module and use the left over money(!) on a more powerful processor.
Here is a picture of my initial prototype. Schematic and source follow shortly.