The shortage in Atmega328 chips is over, at least here at Modern Device. We have programmed  Atmega328p chips to offer again. We have both Diecimila and the new Optiboot bootloaders available. The difference in the new Optiboot bootloader is that it's a little smaller (takes up less program space on the chip) and operates at a higher upload speed, speeding up the upload process. Both bootloaders work well with the BUB. To use optiboot, just choose the UNO setting on the Arduino IDE.

This high performance, low power AVR® 8-bit microcontroller (ATMEGA328P-PU) is programed with the Arduino bootloader. Useful for replacing older chips or making your own ’duino boards. Packed in plastic "chip tubes" so pins don't get bent in shipping.

Specifications of Atmega 328p

• 8-Bit Core
• 20MHz
• 32K flash (program memory)
• 1K EEPROM (non-volatile storage)
  
• 2K RAM (working runtime memory)
  
• 2.7 V ~ 5.5 V Supply Voltage
• 23 Digital I/O Pins
• 6×10 bit A/D Converters
• I²C, SPI, UART/USART Hardware Protocols
• 28-DIP (Dual Inline Package)

Resources

• Datasheet