Research in Wireless Sensor Networks (WSNs) is vast and there are several hardware platforms, many of them compatible with IEEE802.15.4 standard. However, commercial platforms have limited access to modify network parameters in order to test or improve network performance. The paper shows one prototype WSN for temperature monitoring implemented with inexpensive, Off-The-Shelf electronic components (OTS-WSN). The network has five nodes programmed using C language. Each node employs HopeRF RFM12B radio transceiver and Microchip PIC 16F783A microcontroller. This hardware combination is not reported in the literature. Tests performed on OTS-WSN nodes show similar energy use to commercial devices. Our nodes use 14 mA for reception, 3 mA with radio off and 26 mA for transmission with 0dBm power. OTS-WSN features inexpensive, easy to build hardware platforms. The prototype obtained 5% packet loss with a very simple MAC protocol, thus creating space for improvement and protocol testing in a platform where researchers have access to every detail of hardware and software implementation.